We used to own 2 cars now only 1, that's OITK (one income, two kids). I use a bike and car pool as much as possible. Work sometimes requires me to drive but I just plan with my wife the use of the 1 car. I try to pick work and where I live with use in mind, currently in 1 mile from trains, school is 1 mile, Trader Joe's 1 mile, etc.
Ironically, the work which doesn't need me to fund my car usage is flying, I can walk or scooter (Xootr Roma) to the airport and then expenses funds the flight and any transport at the other end, but that is still guzzling aviation fuel so is part of the cause of the problem.
There are some benefits and some downsides. I was working in Sunnyvale and I'd either bike or bike/train/bike from San Mateo, and sometimes get a ride from someone from work, my presence letting them use the multioccupancy lane. Sharing transport is a chance to talk. My bike is a Brompton and fits anywhere on train/car.
As to getting to trailheads well you can use carpooling, helping pay the driver for car costs, if you can get 4 of you then it can become quite low cost per person again, BUT you then have the issue you need to stick together OR agree a rendezvous time back at the car, co-ord pickup times, etc. Not impossible obviously but more detailed planning required.
This issue of car-less though is part of why the last few years I've not been backpacking much, because what to do with the bike at the destination? I've found I've been biking from my home and bike/train/bike/camp/bike/train/bike and just look at the hills from a campspot near the road, with a little bit of loss. I did once find some undergrowth and hide the bike, it was still there when I returned but I was worrying about the bike the whole time.
I sometimes go with others in car, they'll shop or stare at a museum and I'll bike around, I've had some good days out like that although there was one incident I said I'd bike in the direction they were driving, told them to look out for me, I thought they'd be 1-2 hours, but some 8 hours later, I'd done 125 miles by then and dehydrated worried if I popped into a store would be the second they drove past, so its can be a little problematic at times.
Even those who don't have high gasoline costs are impacted ultimately as it drives up cost of food (unless its grown locally), and drive up the cost of practically everything else, and a major part of why gasoline is higher cost is the planet is getting richer, owning more, driving more (1B Chinese, 1B Indians, Brazil, etc), BUT the USA is not keeping up with global wealth because much of its growth recent decades has been consumer and debt driven, and so USA now is relatively feeling the higher gasoline costs.
Best view of that is that the last decades of relatively energy costs has ended.
There is a strong relationship in all of man's history of wealth coming from burning the fuel around, the free energy accumulated over the planet's history such as wood, coal, oil, etc.. As human population increases and per-person average consumptions increases, then that free energy is relatively becoming diluted, manifest by high gasoline costs.
So either ween off energy to a totally different type of economy, or.....
Its interesting, when you fly over southwest, USA has so much unpopulated land, if it got its act together it could make the electricity, and hence hydrogen fuel it wanted from solar from a small part of Nevada/Arizona and pump the fuel around for it to end up in cars with fuel-cells inside which make water exhaust. Water can be desalinated at sea using electricity and then split into oxygen and hydrogen by electricity and so the end of water shortage, end of salination of the soil via tapping water from the bedrock, end of energy shortage. The technology exists but the will doesn't. If the Romans could build viaducts and even older civilisations building irrigation, with all the technology around why can't USA solve its energy problem?
So why doesn't the will exist, that's a more involved discussion best not done in open forums.