But they didn't give you the only tool you really needed: Time.
Having meaningful access to the source is very important, but its value is limited because even small improvements often take a large amount of time especially to code you're unfamiliar with. Once you've made that improvement, maintaining it (or up-streaming it so someone else might maintain it) can take a tremendous amount of time.
I can't wrap my head around this, could you explain further?
They don't have to be engineers. They'll pay $100 / mo to solve it or hire a guy on Upwork to solve it or cobble something together on Zapier + Airtable. The thing is, the tool is insignificant. They don't really spend an appreciable amount of time on complaining about it because it's faster to stop using it.
So why do I tolerate bugs in software like that? Because I know I can fix them. And I also know I won't always. Small gods have handed me tools to remake the world as I would see fit and I do not use them. Are they at fault for not having made the world as I would prefer? Or am I at fault for not using the tools?
In any case, I've noticed a sort of dichotomy among users in their reaction to tools that fail. There are those who go "this tool sucks how can I do my work" and there are those who go "my work is what I want to do which tool can I use instead". The latter set get a lot more done. Once observing this I have attempted to modify my behaviour to be like the latter and have effectively become better.