In my experience of over a decade in the industry i still find that getting real feedback is still not a regular thing. There are multiple things at play here. But there are things you can do.
1. Onus is on you
tell me that getting explicit feedback is more of trying to find yourself and figure out based on action rather than people coming back to you with explicit good/bad (let alone quantitative) and from that, figuring out what was due to your contribution is probably even harder. But as a general rule in one's career, the onus to get feedback is on us then on the customer or management might be coming down.
2. The good/bad balance
Good feedback comes very less. Bad ones almost always. How often have you had tasted a great new dish in the restaurant and rush to the kitchen to appriciate the chef? Against this, how often you had a service complain and yelled back to the call center? You will realize, that typical customers are like Unix commands; when everything is fine usually there is no feedback. When things go wrong you will see a surprise bomb on a Good Monday morning. So in a way, when explicit feedback hasn't come to you, you can actually be a bit relaxed that you never did a big enough goof up that someone will bother you with.
3. Your level in hierarchy matters
Not getting feedback also sometimes means that your higher ups have taken up responsibility of it. In that case, talking to higher up or having open communication repo helps. When you will move up the ladder - most errors will be owned by you and you will see more direct view of it. Many comapanies, don't count lower hierarchy people share feedback thinking that it will unnecessarily move them.
4. Transparency is what changes signal to noise ratio
Many organizations has fat layers across which one cannot see. There is clear hierarchy laid out for responsibility laid out. But things needs to travel only on pre-defined paths. So good or bad, if you are not higher up in the ladder or relevant function of company - you don't need feedback and you don't get feedback. Most often asking customers or sales guys directly might be best best -but it could be a bad gesture or a complete taboo in many organisations. Actually, in a startup like companies you can always openly discuss the matters. But that also depends on your initiative to ask more relevant people. In all regards, it is the habit to ask (harmlessly) will give you some feedback.
5. Quantification needs systems
In many companies, systems are inherently geared up on processes and quantification. When your core processes or systems are more tacit by nature it is difficult, costly and sometimes quite artificial to generate this information from this. As Yannis pointed out, when there are no measurements in the system to start with, asking for quantified measure might be pointless; but if your organization is open in communication, seeking explicit feedback is more of the tacit form and you can seek that from people who you trust.
What is important is to get to know first what was the overall fate of the project? What elements were good or gave problems, and did we do well for time and budgets. This are sometimes easy to answer but difficult to measure.
6. Feedback against expectations
Sometimes what we really care about is how much of our work is aligned to the purpose of the larger objective or not. It is different from knowing whether we are doing a good job or not. I know of cases where a young guy works out of his way and what he thinks a homerun, ideally should have been done much more systematically by more or senior people. The point is, there is a difference between (self) appraisal [how well you could do against your caliber] and end user feed back [whether customer had any help from this work]. Both this things match only when your profile is perfect fit against customer expectations on your job. This looks obvious, but rarely true in real life.
7. Understand the bigger picture
Quite often, people take things granted when they see things obvious. You will see many peculiar departments don't receive value because they don't participate (or are not allowed to participate) strategically. Admin guys, IT guys, even HR guys sometimes stand by the wayside and people keep watching the finance and sales guys taking up the center stage. It is not that company will not work without them, but it is not the core business of the company. In my opinion great many people should outsource stuff - but that is not always true. The same function could be very valuable in other companies. So if you part of that dock, you won't expect much feedback for yourself. If you take up career where your function becomes the core department (or controlling one) you will see lots of feedback even if you didn't ask for it.
8. Everyone is busy
The higher ups are always busy. Either they are busy fighting lot of pressures to meet demands or they are busy dreaming and expanding. Only organization who is not extreme hungry on growth but still do great job in holding existing customer well, actually have a real channel of feedback after relationship evolves a great time. More often than not when we see customer walking out suddenly is a sign that no one really bothered to understand their problems. It is when strategic functions of business are jumping in the focus, real feedback doens't come to business itself, let alone the last curious guy!
Sorry, if this was too long -but i think this is a real challenge in most places i have seen.