No, there's no principle, there's a ~20 minutes old idea that we engineers are so obviously awesome that companies should actually be paying us for the privilege of interviewing us.

There may exists engineers obviously awesome enough for that to be feasible, and great for them (but they are probably also obviously awesome enough to not have to go through coding tests, so it's a moot point) and even if I could perhaps (judging by certain recruiter-emails) scrape by as one of them, I certainly couldn't five years ago.

Back then, if I'd had to be good enough on paper alone to warrant not just being put through the recruitment process, but to be paid for it was well, I am not convinced I'd have been considered (and yes, I did a take-home test, and I aced it and it made up for my near-total lack of on-paper qualities).

Of course, companies shouldn't waste their applicants time with needlessly extensive tests, but there certainly exists no 'principle' by which you have a claim to be reimbursed for spending a few hours on an application.

I have had a few of these the last year or two. Never been paid. More than half of them are a waste of time. I have refused quite a few of them.

The last "shouldn't take you more than two hours" exercise that I was given involved jumping through hoops to get set up on Instagrams API, only to discover that I was in a sandboxed mode, and needed my account approved before i could get anything more than metadata out). I didn't even get started coding, so I am not sure what exactly the test was meant to achieve.

I was not, at any of them. Yes, I was effectively giving them my time but it doesn't sound unreasonable when you compare it to the alternative: I'd spend that same time answering whatever obscure coding questions or far-fetched exercise they had but in a far less comfortable setting (and arguably less representative of my skills). Not to mention how I'd probably have to do the interview at a time they're working, instead of doing it on a snowy Sunday evening, at my discretion.

I'd so much rather do a project with my own tools and from the comfort of own home than commute several hours across the city for a several hour interview.

If all it required was an hour phone call and a small project, I'd totally do it for the right company.

I'm too well-paid and busy to do interviews.