Isn’t ransomware trivially preventable by backing up files, and having a completely different security procedure and credentials for modifying backups than doing anything else in the system?
This is the case for basically any transactional/accounting system.
If you lose even one day's data, if often would make more sense to pay the ransom than try to reconstruct the transaction flow for that day (or portion of the day) that was lost.
Imagine you restore your backups (taking a whole weekend) but it turns out the ransomware is some kind of kernel-level hack that also patches ls to lie to you about file being there when they aren't (as an over-simplified example). Once you realize this you can switch to another tool and pinpoint where things are going wrong, but now restoration takes twice as long as before plus the farther back you go the more commercially valuable data you lose.
You don't even need to compromise the backup software, as long as it looks like you might have done so.
Ransomware also targets individuals, which typically don't have the knowhow to sanitize their computers. Since our industry is kind of not caring about security wrt consumer goods, they're left to fend for themselves.