It is exactly like you suggest with the other teams. It starts with the local city and state and the officials there. Perhaps what you're suggesting is that MLB adopted a blanket policy this past year that said no fans -- and that was done for a couple of reasons:
1) To create a level playing field for all teams until they could sort out the finances of some teams selling tickets and some teams not selling tickets.
2) The legal aspect, as MLB didn't want to be liable for a superspreader event. You can understand why a business wouldn't want to put itself in jeopardy of such a thing.
3) More information. When baseball launched on its plan to have teams play at home, in their ballparks, there was a lot of unknowns about the virus itself. There wasn't a vaccine on the horizon. Heck, we were still all talking about flattening the curve, and Major League Baseball made a conservative call based on the information they had the time and they could apply to all teams at that moment. They wanted to be conservative.
Now, they're starting to change. More information. More understanding. More time to come up how they're going to handle 20,000 tickets sold at a Rangers game vs. 11,000 at a Cardinals game vs. zero at a Diamondbacks game, or however the various places work out what they can and cannot do based on the virus in their area and the policies of local government officials.