In the UK you do handbrake starts as a part of the driving test. They’re not useless because if you don’t know how to do it, then you’re going to roll back or cut out when you start off and that’s a fail. Hence why they’re part of the test. Typically, you apply the parking brake, release the clutch enough to “bite” and hold you in place, release the brake and continue to release the clutch as you press on the accelerator. All in a controlled fashion.

Of course, fancier cars have hill start assist and electronic parking brakes these days so I don’t know what happens if you show up for your test in one of those - they probably just do the test anyway because I’m sure people still manage to screw up.