Gun Control & RKBA

can't be compared to safeties on rifles has to do with the heaviness of the triggers.

You have noted that rifles almost always have manual safeties, and that is true. It's also standard practice to engage the safety on the rifle whenever it isn't being shot. However, rifles - especially hunting rifles - have lighter triggers than handguns. Rifle shooters typically try to get their triggers down below 3 pounds. 2-pound triggers are common on rifles. Some rifle triggers are measured in ounces rather than pounds.

Handguns - unless they are exotic competition guns - are never sold with triggers this light. Police and members of the public that carry handguns typically walk around with 6 to 12-pound (!) triggers, and that includes the Glocks and similar designs.

There is a practical limit to how heavy a handgun trigger can be, since it is very difficult to shoot accurately with a heavy handgun trigger: having to apply a lot of force with your trigger finger makes it hard to keep the barrel pointed where you want. The extreme example of this is the NYPD, which specifies heavier-than-standard triggers on their guns. For this exact reason, NYPD officers are notoriously bad shots. In one especially notorious incident a few years back, 2 NYPD detectives wounded NINE bystanders in the process of shooting ONE suspect, who wasn't that far away from them.

In short: the relatively heavy trigger on a handgun acts as a safety. Most handgun manufacturers already produce such heavy triggers that the trigger is the biggest factor in poor handgun shooting.