I’d assume it depends on the event. for GAA matches you need permission from their Media officer, for rugby you need it from the IRFU, soccer would be the FAI.
Each governing body would have it’s own criteria, and may depend on demand for any given fixture.
One example for thomond park & munster rugby, precedence goes to the major sports photo agencies, national papers, regional papers, then freelancers. If there are too many photographers requesting access then the freelancers don’t get allowed pitchside.