Running some tests and if you set a company in USA set in the Tri State to the minimum requirements to be "large" they can draw 50K+ to pay per views/big shows. This isn't something you can adjust in the era settings. It's not just a realism/immersion thing that sucks to see these wild attendance numbers, it also makes it almost impossible to struggle with a big company because you can make so much money in gates.
Before anyone says "well maybe the companies shouldn't be that popular in the database!"...if you don't make them big, then they don't count title reigns to the HOI formula. So 80s and 90s mods can either have 60k people showing up to big events every time you hold one OR Hulk Hogan, Ric Flair, Vader, etc. never record a single point to the Hall of Immortals.
Either an era adjustable thing or just a lot of rebalance work on how events work. Even regular shows are too inflated as it's easy to get 10k to any show, but that's livable.