Ever Deteriorating Quality of Theme Quality & Support

I remember when all you have to do is simple upload xml file and you can have a working demo of the theme in minutes.

Now after several failed tries, you have to open a ticket at the author support and then wait for days for them to set up the theme which still needs some work to get it look like the demo version

I recently asked one of my clients to buy 3 themes for his websites and all 3 have some trouble.
The first theme child theme is not working and the support is horrible
The second theme author/support took 2 weeks to get the demo up and still has some issues
The third theme needs several modifications even after the “complete demo” install

Is there anything the buyer can do about this ?