Thanks for the comments. Speaking of parking lots, If you ever want to see the need for the shuttles, visit the park the week before the shuttles start. A parking lot is what the entire Zion Canyon Scenic Drive looked like the day before they started the shuttles in 2014. Cars parked on both sides of the road hundreds of yards on either side of the usual stops. Many section one lane only. I'll never do that again!
While I don't like the shuttles, many of the national parks are getting so crowded that they are necessary. I prefer to have my vehicle (with my gear) handy when I stop to take photos, but that is becoming an impossibility in many parks.
Some of the parks have photographer's passes - for example
Denali that let you drive your own vehicle. A bit too expensive for my budget, plus I probably wouldn't qualify, but I was very envious of the guy camped next to me as he drove by me while waiting for the bus!