As others said, user != customer. A big chunk of software (perhaps the majority) is bought by someone other than the end-user. Think workplace, or all the OEM garbage that ships with your phone.
On top of that, on the mass market, customers don't have a meanigful choice. They can't signal desires in the entirety of concept space; they choose out of what's available on the market. Which means the choice really lies with the vendors.
And they do, even if it's not a conscious decision. Most large scale experiments see bounce rate increase and revenue decrease with page load time. More load time because "it's easier to develop this way and it saves developer time, which is expensive" means more bounces and less sales.
Of course, that only matters at scale. If your site never takes off, optimizing for user experience (instead of developer experience) wouldn't have paid off. On the other hand, maybe putting your users second lowers the chance of it being well received.
This (and related phenomenon with subscriptions) is arguably a big drive for the software becoming increasingly infantilized; shiny toys instead of useful tools.
On top of that, on the mass market, customers don't have a meanigful choice. They can't signal desires in the entirety of concept space; they choose out of what's available on the market. Which means the choice really lies with the vendors.