Yes, there are various bots, and some of the large US companies such as Perplexity do indeed seem to be ignoring robots.txt.
Is that a problem? It's certainly not a problem with cpu or network bandwidth (it's very minimal). Yes, it may be an issue if you are concerned with scraping (which I'm not).
Cloudflare's "solution" is a much bigger problem that affects me multiple times daily (as a user of sites that use it), and those sites don't seem to need protection against scraping.