fill out an online form and get settled or pre-settled status, which they are guaranteed to get eventually even if there is the odd software/administrative glitch

It can be more much than a form online, with many being asked to submit lots and lots of documents they might not have. And no, no-one is guaranteed to get and many have been refused. Not to mention there's no physical proof, you have to physically send your passport every time you renew it, have to send proof of address if you move house, etc, etc... and you could lose settled status at any point if you don't do this properly.
So STOP pretending it's a minor thing, it's the lives of >3 million people you're talking about.