Latecomer said:
That's kind of how I see it. Time is money and if someone is willing to spend some of their time helping me out, then I feel they should be compensated.
That points out why the situation is bit tricky. Part of the rationale of recommendations is to given an evaluation of someone's abilities, and it's often the case that having a friend that wants to help you out is the worst person to do an evaluation. Sometimes, the person whose opinions you really want are someone that hates your guts and wants to do anything they can to make your life miserable.
The other thing that happens is that if you are in a system with recommendations, then a lot of doing well in that system involves the ability to make friends and have people like you. That can cause conflicts in situations where technical ability is part of the equation.
One weird thing is that in Chinese applications to US universities, it's common practice for the student to write their own evaluation and then have the professor sign it. The system works pretty well, and one subtle implication is that if you end up with a glowing recommendation, you *don't* owe the professor anything, since you wrote the recommendation.
One reason that it's socially awkward for the professor to write the recommendation letter is that it's considered bad form for a professor to say anything bad about their students. However, because there are social pressures to be humble and modest, it's considered bad form for a student to say anything positive about themselves, so having the student write the recommendation typically results in a more negative evaluation.
Something else that I've also not fully understood is why recommendations are never used in industry. I think the theory is that anyone that knows someone well is fundamentally unqualifed to evaluate them. The standard procedure in most companies is that you can introduce a friend, but that the person introducing the person stays out of the evaluation process. It's also standard practice for a company to pay someone a few hundred dollars if they introduce someone that gets hired.
One big difference between academia and industry is that in academia, everyone knows everyone else. In most research faculty searches, if the committee hasn't heard of you before you submit your application, then you are not qualified for the position.