The shower head regulations are federal, and became law almost a quarter century ago.
If your shower head is trickling, then you have a shower head that isn’t working well, and you should replace with one that does, it is what I do for my customers.
I have replaced a lot of showerheads and they are not all defective. It was a plumber who told me about widening the hole. The only shower heads that work right are either old or drilled out
Youre being deliberately contrary.