The regulation is to prevent the HOA or landlord from requiring prior written permission if it would cause an unnecessary delay. It does not say anything against the installer requiring prior written permission (to protect their own butt) before doing an installation in a HOA. If the customer does not like it, they can always find another installer that does not have such a policy, or do a self-install.
How could the installer be liable for anything in a HOA?
Been doing this for 20 years. You don’t install in an apartment without covering your butt.
Single family home, you should ask if they own or rent, but generally in this situation there are no issues even if they Rent.
If the customer owns their home, then they can do whatever they want. It’s their problem if the HOA wants to cause a problem.