The people that fit something and the people that fix something are usually different people.
The people that are paid to fit are not necessarily incentivised to pay attention to its maintainability, especially for products that take a year or so to break. Their clients have already referred them on.
They are two different skill sets. “Just do both”, but both are full time professions. I wonder what it would be like having a guttering cleaner watch/manage the guttering installer. “Oh, have you thought of this? I see that way fail a lot”.
One way to align motivations is to have warranties. This still does have the same problem that the work is done to purely hit the warranty length.