If all companies followed this policy, the cost of looking for a new job would basically be prohibitive.

It almost already is! 'Homework tasks' are possibly my all-time gripe about today's tech recruitment process. I can't count the number of jobs I've taken an interest in, only to be told, "no, you cannot speak to a human being before spending three or four days on a speculative coding task" - several days of work for a job I don't yet know I want, working with people I don't yet know I want to. I get this stuff happening before I can even confirm things like day-to-day responsibilities and salary expectation - the absolute basics. It's absurd.

The great irony is that my current employer, The Guardian, was the most ambitious application I made, yet simultaneously the most relaxed and sensible process of all. A face-to-face interview, a two-hour technical assessment, an opportunity to explain it and a pair programming session. They even offered to let me come in during the evening.

Compare that to being asked to spend "up to a week: if you like" (translation: we expect you to spend a week) on some generic JavaScript Blackjack game, being harassed by recruiters, expected to drop everything for an interview the next day (HINT: The things that make me desirable as a developer also mean I have commitments at work), and only then discovering you'll be working on some kind of improbably miserable legacy system.

And it isn't even necessary. I have a Github profile. I write open source software. If you want to see the kind of code I write, the kind of technologies I use, the kind of things I care about, you can look, look right with your eyes, right now, at actual code I have actually written, and judge for yourself whether you like it.