There's no universal or legal requirement for a minimum number of interviews. I've known plenty of people that interviewed exactly one person for a position before hiring them. In some cases they were the only applicant, and a minimum interview requirement would have prevented them from filling the position at all.
Some organizations have their own requirements, typically described as an effort to avoid favoritism/nepotism (whether they accomplish that goal is questionable). It's not uncommon to have an interviewer that's clearly going through the motions to fulfill a requirement and already has another candidate in mind. While this is certainly frustrating, it's also helpful to the interviewee. It highlights that this is a company that values process over efficient, meaningful results, which can be an indicator for what your life might be like if you worked there.
In larger companies, the hiring process can look something like this. A team puts together a list of skills/requirements that a new team member would need. Their manager uses this information to write up a job description. This gets passed to HR, who cleans it up, formats it to the corporate template and adds a bunch of fluff that nobody reads, and then posts it publicly. Normally, that process is fine. When it comes to STEM fields, though, it's common that neither the manager nor the HR employee have a technical background. They don't completely understand the technical requirements given to them, and it's incredibly common for them to leave off something they don't realize is important, or reword something in a way that completely changes the meaning. For example, I frequently see postings for programming positions that clearly do not understand that C, C++, and C# are completely different languages and not a single skill set. Most non-technical people can't tell the difference between "big data" tools and Pokemon. I've had plenty of candidates passed to my team that passed HR's screening, but didn't fit the requirements at all because HR didn't have the slightest idea what anything in the job posting actually meant. The hiring manager is supposed to screen the applicants as well, but rarely have time and instead trust HR's judgement. Sometimes all the manager actually gets is a profile in a candidate tracking program that was created by a machine attempting - often incorrectly - to extract data from the resume or LinkedIn page. That leads to the situation that you described, where you get to the interview stage and your interviewer isn't even familiar with your resume. It's a problem caused by too many middlemen, an over-reliance on technology, and by managers not giving hiring-related tasks the same level of priority as their "day job".
Recruiters can make this problem even worse. Recruiters try to protect the identity of their clients (so you can't bypass them and avoid their commission). They'll take the job posting, remove any information that could be used to identify the company, re-work it to fit their agency's templates, and extract what they think are keywords. Candidate resumes also get sanitized, removing anything personally identifiable and getting reworked so that the company can compare candidates more easily. Like HR people, recruiters are generalists and also rarely have a technical background. Every time they touch the job description or resume, they inadvertently dilute the content and important information can get mangled or lost. The candidate sees a mere caricature of the original job posting, and the hiring manager only gets the CliffsNotes version of your resume (another reason to always bring a printed copy to the interview).
As annoying as situations like this are, they're relatively minor when compared to many of the other problems in the modern hiring process. The inverse to your situation is even more problematic: how many candidates that were perfect fits for the position got erroneously filtered out and never reached the hiring manager's desk?