It’s a skill that has to be learned. To be learned, one has to have the opportunity to learn it.
That takes time, usually transportation, energy (of the person), and knowing what the quality of instruction is in the area they’re trying to learn in.
Picking things up irregularly isn’t the same as knowing first aid, though it’s here than nothing, and some things are just as good learned that way as formally. Don’t need much in the way of lessons to apply pressure to a wound, and that’s enough to keep someone alive long enough for someone with more training to get in place. But doing CPR does take a bare minimum of training to be certain of it being effective.
So, nah, I’m not going to think less of someone for not knowing something. Nor for not being well trained at it.
Now, I have insisted that anyone I live with have at least CPR, Heimlich, and stop the bleed under their belt. I can handle anything else, and my crippled ass is the least likely to be out of the house, so it’s all about the bare minimum for when I’m injured, or they’re out and get hurt so they have time for ems to arrive.
My wife already knew basics from a new parent first aid class she got when her (now our) kid was still in utero. Infant and toddler focussed, but still. My dad still remembers his training from his army days, though some is a little outdated. Our kid has the bare minimum, but plans on taking a more comprehensive course next summer.