Riding around with a loaded gun in the truck safety off is a piece of foolishness. People have been killed by accidents stemming from that. If you can't remember how to knock off a safety on more than one type of gun than you should re-examine your decision to own guns. I've been shooting guns my whole life. They all have different safeties, and I'd never think of riding around or leaving one lying around with no safety on.
And before the glock and revolver crowd come with pitchforks and torches, yes I realize that they do not have safeties. I'm talking about shotguns and rifles with hair triggers. And 1911's. I'd never leave a 1911 lying around hammer back safety off.
Accidents can and do happen, and there's no going back if someone dies.