I don't agree. These things actually matter. A developer who isn't told otherwise is just going to do whatever they feel like, so if there is nothing or no-one enforcing the standards, then the failure isn't on the individual developer, it is on the team lead. Someone needs to be setting the standards.

In the company I work for, there is a team that has isolated itself to some extent from other teams and works at a furious pace to keep their particular section of the business happy. We're lucky enough that they spun up their own repo to do their work on, so they don't actually impact other teams, but if the quality of the commit messages is anything to go by, I am 100% certain they're going to end up in a huge mess, if they aren't already. The team lead encourages this, and certainly doesn't care about commit messages etc.

Developers who care about other developers tend to write better quality code, because they care what other developers think of them. If you care about other developers, you will most likely write decent quality commit messages too.

I have seen over many years the types of developers who only care about moving their own code into production as fast as possible and getting to the next thing. There is a very high correlation with a mess at the end, which they inevitably won't have to tidy up because they'll be doing the next thing. These types of developers hate owning stuff in production, so they don't do it, so they don't actually care how maintainable their "clever" code is. I am very certain that a number of people reading this will be those types of developers.