Your question made think of issues that may be more of a philosophical nature, but hopefully will be 'food for thought' as your career progresses... which I hasten to add - I wish you well with. At least you have thought about life and made the effort ask a question. So that will help you just in itself.
I'm 66yrs now, and back when I was about 15yrs my father asked me "How much will an employer pay you?". I'm an engineer and scientist by aptitude, interest and training so even at that young age I began trying to answer what appeared to be a vague question. Anyway, he put me out of my misery by answering "The minimum you are prepared to accept." And on reflection I think it's very true.
I have worked in Aerospace, automotive engineering and software development but completely failed to recognise I am suited to R&D. This realisation only transpired by accident in my 50s but the reasons are not relevant here. I think the following comments need the reader to know this.
In my 40s I read a book "Winning at interview" (WAI) Winning at interview and it totally changed my understanding of the employer / employee relationship. I was the typical employee with 'employee thinking' up to the age of fifty; then partly as a result of not understanding the roles for which I should have been applying, I jumped into self-employment. And that changed my view of the 'world of work' yet again. I was self employed offering heating and plumbing services to the public. This meant I was totally dependent on explaining the problem to the customer and suggesting a solution.
Initially I approached people as though I was in the technical offices at the various companies for whom I have worked, which drew the complaint that I was 'too technical'. So the battle was meeting my potential customers (employers) on their terms at their level of understanding. And then perversely, once 'reel in', customers tended to stick with me through thick and thin rather that risk finding another tradesman.
Understanding people is not for the faint-hearted. But it's essential.
You need to be with an employer who knows your value and who values you.
The employer has the whip-hand; you have to ensure that you understand what it's costing him to employ you. If you started your own company and began interviewing potential employees, for whom you have to pay a salary, for offices, for computers, for benefits, for sickness etc etc, your viewpoint would change totally to that of the 'employer'. Employees need to understand their employer and "TELL THEM" they appreciate their difficulties.
Over the years I have observed people in the 'employed' category acting as though employers OWE them a job. They seem to find it all too easy to have a "gimmee, gimmee, gimmee" attitude; and employers sense it immediately. I don't mean that I sense that about you. It's just a point I want to make.
You will be, at least, employed by virtue of your attitude and understanding of the employer's position, as much as on your worth in terms of skills and abilities.
We have to realise that if we are worth our pay then offering a 'cut price deal' to an employer may well backfire. Will he think "This guy actually questions what he is worth." And what is the 'cut price deal' supposed to achieve? Is the employer so poor that a saving of £10k (or whatever) will keep the company afloat? If so, do you really want to work for them!? If the employer is happy to accept an employee working for less pay, then what does that say about the employer? If you were the employer, would you want your staff struggling financially?
And one last point: I find that programming tends to cause us to place the most important part of thought process at the end. My rule is "Re-read and move the important point to the beginning." So to quote you- "Is offering low pay work for a trial period ... a good idea?" Your point is "Is it a good idea...?" The concept of the "good idea" envelopes what follows, so say that first.
I hope these ramblings help. Do read the book.