With tiled roofs its honestly not so bad. As long as the installation hooks and overall kit you have is good ofcourse. It took me and my friend like 2-3 days of hopping around on the roof with little prior experience. Before we closed it up we had someone professional attest it which cost a tiny fraction of what letting them install it would have cost.

But i generally agree, there are lots of shitty companies for both equipment and installation that just rip you off.