***can still purchase guns easily in supermarkets,”***
I remember those pre-1968 days! Hardware stores, grocery stores, clothing stores, sporing goods stores, saddle shops, gas stations, and many others had a gun counter with all sorts of rifles, shotguns, pistols. Tons of Army surplus rifles and handguns. Cash and carry.
Age limit was usually 16 for firearms, no age for ammo purchases. No background checks, no waiting periods, no forms to fill out, across state line sales no problem. The USA was awash in guns.
And crime was very low back then. Then the politicians began to stir the pot.
“Then the politicians began to stir the pot.” Leading one to believe politicians are half of the problem, useful idiots being the other half.
They had help from the Russians.