My entire (decades) career I worked primarily in small start up teams, and even when people didn't see eye to eye, they always maintained these kinds of basic practices. I think a lot of disagreement on these expectations is rooted in the size and "tight-knit"ness of your team.

I think size of the code base matters a lot too. In a multi-100k line of code application, you might not know a utility function is already defined somewhere and reinvent the wheel.