I won't pretend that there are no exceptions to the pros for public transport. Cars are there for a reason too. Sometimes combo is the best [0].
From stereotypes - I'd agree that LA's public transport is orders of magnitude worse than travelling by car. Though it sounds like OC actually never been in a moderately dense European city. You often _cannot_ go directly to your destination with a car [1] and your travel will often take longer [2]. I probably won't be wrong by saying that it will be an order of magnitude more expensive too [3].
If it's a big city - driving will cost you greatly and you will lose time. If it's a moderate city - driving will cost you a lot and maybe it will take similar amount of time. I don't see where it is a win for cars here?
> convenience of putting a large amount of shopping / luggage in the back
How often do you go shopping/carry luggage to the amounts you can't carry? Personally once every week or two.
P.S. I know that there could be exceptions to the rule, but I had in mind travelling inside the cities for common scenarios as going to work to the city centre.
EDIT: Forgot to add. While going with public transport it's great time to catch up on latest podcasts, scroll news, even do minimal work if that's necessary (emails, chats, etc.) or you can just chill in general. Driving will need my 100% attention on the road and probably 80% of the time will make me super stressed and angry.
Also "this new Musk tunnel thing." - I think I wasted a comment against a troll. :) Musk tunnel is a "metro" with significantly less throughput and traffic jams: https://www.youtube.com/watch?v=p8NiM_p8n5A
[0] Often businesses are based in big cities, but a lot of people live in the surrounding area. You drive to the city limit, leave car there (often rather cheap/free if you use public transport) and hop onto the express train that takes you to the city center very fast.
[1] Good luck to park your car in the centre of London, Paris, Berlin, Amsterdam, Copenhagen, Stockholm, etc. and if you could (e.g. office building has parking) - it will cost you dearly;
[2] Traffic is prioritised for public transport. Separate bus lanes, some streets don't even allow cars, priority for trams. Leaving your car is a nightmare too.
[3] Fuel, insurance, road tolls and/or car taxes, maintenance and car price itself, parking.