Yes, when I bought my car it had a fire extinguisher and first aid kit.
I moved the FAK to the glove box where I can reach it from my seat

Regarding people, many or most are complacent and may be upset if you shove things into their cars. The only scenario where it will be great news is when someone is stuck in a blizzard and call you , then you give them the surprise that you have hidden a survival kit in their trunk. But most likely scenario is that they find it in the trunk and be upset about you being so intrusive in their lives.

Sad, but this is how life goes.

Last month I gave one of the kids a few tools, and they still sit there collecting dust. He never thought of putting them in his car or even his desk drawer. If he has a problem one day, I don't know what he will do, but most likely he would use his smart phone to call a technician or something.