Because Disney adheres to extremely strict rules and regulations for distancing and mask wearing. If you aren't wearing your mask, you can be thrown out. (Unless you're in a designated eating area.) Rides stop when masks are taken off and will not resume until the mask is back on.
The image below is a super spreader event where it is likely that half the people there would wear masks and the others wouldn't. They are also sitting RIGHT next to each other.
Also of note, Disney in CA is not open, just FL.
