I'm an eagle scout from the days before they started accepting girls, I remember always hearing about how much cooler the BSA program was than girl scouts

Part of the problem is with how things are structured. BSA troops tend to stick around for a a while (the troop I was part of well over a decade ago is still going strong and just a couple years off from its 100 year anniversary,) so you end up with a lot of accumulated knowledge and resources over the years, people stick around after they age out of the program to stay on as leaders, they bring their own kids into the program years later, we had some 2nd or 3rd generation eagle scouts who had all earned it from the same troop their fathers and grandfathers did, we had a garage full of troop gear, a pretty decent troop library fell of merit badge books, old handbooks, various first aid and camping manuals, etc. some troops have their own cabins or campsites or other such properties, and the organization makes it very easy for new scouts to find an existing troop, pack, crew, ship, etc. to join.

Girl scouts often don't have that. Sometimes they do, and when they do they can actually do a pretty amazing program, I've heard of some girl scout troops who've done some pretty cool stuff that honestly puts my own troop to shame, but more often they kind of tend to get formed with a group of girls around the same age and their mothers, never really do much recruitment, and when the girls either age out or lose interest and drop out the troop just kind of folds. They have to put a lot into the cookie sales and fundraising because they're usually starting with no troop gear or other resources, there's not much generational knowledge about how to run a scouting program, so they tend to just kind of have to figure things out on the fly. And a key part of the boy scout program was "boys teaching boys" the older kids in the troop take on leadership roles and help run the program teaching the younger kids, if you're starting with a group all about the same age, you lose out on a lot of that dynamic.

Also as far as recruitment goes, at least back when I was in scouts, even if you waned to join an existing girl scout troop, it could actually be pretty hard to find them. BSA had their BeAScout website, you could find all the local groups, meeting schedules, and contact info pretty easily, girl scouts, at least at the time, didn't have anything like that. I remember there was one time my troop wanted to reach out to some of the local girl scout troops to see if they wanted to participate in some kind of event we were having, and they had a hell of a time finding any contact info for them.

Also, some of the girl scout leader training requirements seemed a little excessive, maybe the situation has changed, but I remember hearing that they had to have leaders with specific training for pretty much any little part of their planned activity, like there was a specific training to go on camping trips, a separate training if you wanted to have a campfire on the camping trip, etc. and a lot of them were paid courses and I don't think they were cheap. I don't have anything against training in general, I had to do a few when I was a boy scout leader, but some of what I heard from the girl scout side of things sounded pretty excessive to me.