> For professional use, that is just unacceptable. If you rely on your computer for income, you can't wait that long.
This may be an unpopular opinion, and I don't mean to sound dismissive or suggest that waiting 3 weeks is normal, but I do think it is incredibly unprofessional to rely on a single device like that for work. If it's truly an indispensable part of your job, you should have a backup--that goes for anything, not just computers. It could be a 10-year-old hand-me-down or a cheapo Chromebook, but you should have a backup plan.
> Other brands (HP, Dell, Lenovo) offer on-site same day repair service. They send someone to your location and if they can't fix it on site, they'll give you a replacement/loaner. For me, that service is well worth the cost. If only Apple would offer that.
When I was first getting started as a programmer, I made most of my income by doing tech support, rather than actual programming. A large percentage of the cases were people hiring me to deal with the likes of HP, Dell, and Lenovo because their "on-site same day repair services" were absolute garbage about 50% of the time. You could get a laptop with a DoA hard drive, but they'd refuse to replace it unless it failed their specific check, which was always inadequate. It was normal to argue with them for 6+ hours about it. You could put a fresh drive in to demonstrate that the issue was gone, but they'd still refuse to do anything. It wouldn't matter if it BSODed consistently with a fresh installation on their drive but not on the drive I was using for testing, or if the SMART results were the worst I'd ever seen--no test fail, no replacement.
> IFAIK Apple does not offer such service (unless you have >50 devices).
It varies widely depending on location. If you go to a large, busy Apple store, they tend to have a lot more parts on-hand; it doesn't need to be in Silicon Valley as long as it's big. If they need to order parts, they'll give you the option to hold onto your device until the parts arrive. I've gotten apologies when a repair took longer than 24 hours. I tend to prefer the Microsoft store method, though: when I've had issues with Surface-series devices, they've never attempted to repair it there; they just hand me a new one. It's hard to beat that. (I guess Apple's approach is better if you need to recover your data, but I never save anything valuable on a single device.)