"it's better for the company that I don't try, my time is expensive and any minute not spent on a feature is a waste of my salary" - is a common justification that I hear all too often.
Maybe the people who care this much about performance should start competing services or a consulting firm which optimizes for that. Better yet, they could devote their efforts to helping create educational content and improved frameworks or tooling which yields more performant apps.
Surveys could be used to explain the bounce rate, but getting feedback from people who leave is one of the hardest the recruit well for. Usability tests could help with that though.
This “blame the managers” attitude denies the agency all developers have to do our jobs competently or not. The manager probably doesn’t ultimately care about source control or code review either, but we use them because we’re professionals and we aim to do our jobs right. Maybe a better example is security: software is secure because of developers who do their jobs right, which has nothing to do with whether or not the manager cares about security.
Secure software happens because of a culture of building secure software, or processes and requirements. NASA doesn't depend on individual developers "just doing the right thing", they have strict standards.
I believe there is some nuance to this due to the winner-takes-all nature of modern software services. There simply isn't a lot of choice for users or switching is expensive so companies don't do it and employees are forced to suffer through horrible performance.