As I recall I had no issue during PowerPC and Intel Mac transitions. It has been over a year since M1 Mac came out, why there are still lots of software, including those from well established big companies, that have M1 version still underdevelopment with no timeframe on availability? Didn’t Apple provide them hardware long enough for development?
It took a long time for some PPC software to move to Intel as well, and of course some never did.
For lots of software it might just be a recompile so, if it's under active development, an ARM version will come out fairly quickly - but for others it can be more complex.
* It might use third party libraries for example, and there are restrictions on mixing code, so the app has to wait on someone else who may have different priorities.
* IIRC Autodesk said they had to move their OpenGL code to Metal as part of the transition. I'm not sure why as I thought that, while deprecated, OpenGL was still available, but I assume they know what they are doing. The more general point though is if you were relying on a library or facility that's not even available anymore then of course rewriting your code to use something else can be a lot of work.
* If you have an old code base you might also find there are lots of hardware assumptions built in that need sorting, in parts of the code no one has looked at in years. I imagine unaligned accesses might be problematic on the M1 but you can usually get away with them on Intel.
These things are all difficulties, and then, as others have said, the economics needs to make sense.