Very interesting. By the time I started working on cars myself (1969), Sears had a pretty comprehensive selection of metric tools, individually and in sets. I got by for years with a 3/8" flex handle and a set of sockets, plus, when I could afford it, a set of combination wrenches. Craftsman were my standard tools: affordable, high quality, and, back then, they took their lifetime warranty seriously. I can't tell you how many flex handles and sockets I replaced, broken trying to remove the lug bolts on a VW bus.