There are lots of tools that allow you to generate what are essentially lock files. But I think what the previous poster is saying is that most people either don't use these tools or don't use them correctly. That certainly matches my experience, where I've seen some quite complicated projects get put into production without any sort of dependency locking whatsoever - and where I've also seen the consequences of that where random dependencies have upgraded and broken everything and it's been almost impossible to figure out why.

To me, one of the big advantages of UV (and similar tools) is that they make locked dependencies the default, rather than something you need to learn about and opt into. These sorts of better defaults are sorely needed in the Python ecosystem.