But that would be a lot of work and the damned user could reply or update their review that “it still doesn’t work and my review still stands”.

If you control both the product and the platform, deleting negative reviews is much more convenient than actually resolving the issues.

Any company that thinks it's too costly to respond to paying customers better have a really good ads product or airtight enterprise licensing deals. Because that's the only type of revenue stream where you can get away with ignoring the user.