Could we add HVAC manufacturers to this list? They don't want to sell you anything such as replacement blower fans, etc. unless you are a "licenced professional". And if you do somehow manage to get a unit or part, all warranty is void This is complete rubbish as there is nothing complicated with installing a replacement fan, etc.
This is just another example of the current control freak society who thinks nobody should be able to do anything for themselves and we all should be completely dependent on "professionals" who they can further tax (license) and control to make themselves feel more powerful.