re: Could most legal cases be solved without a lawyer?

Sure but you can’t advocate for yourself well. At least 99.9% of people can’t.

Your scenario is no different than any other job people normally hire others to do for them. Technically sure you can do it yourself but it’ll probably go poorly.

If your premise is that it’s easier for a random person to do a lawyers job than it is for a random person to do other jobs that they have no training or experience doing, that’s just wrong and you have a fundamental misunderstanding of what lawyers do and how the legal system operates.

And to be clear in a first time DWI or simple battery case you’d probably be offered a pretty straightforward plea deal with no jail time. So you are right in the sense that it probably doesn’t make sense to hire a lawyer bc you’ll just take the plea deal. It only makes sense to hire a lawyer if you want a better deal then what you’re being offered or want to fight it entirely.