Floors and their traction level are in fact already regulated as part of ADA for many buildings. And there's tons of building codes regarding your residential bathroom for similar safety issues - minimum clearances, height of fixtures, anti-scalding valves, types of glass.

As others have pointed out, the entire building code is basically a balance between cost and safety. Anything having to do with egress tends to get extra attention, as well. If there was a zero-cost way to prevent slips and falls, it might well end up in the building code, yes.

>> Maybe we should ban slick bathtubs, tile floors, and raised floors.

You can usually look on the box and find the coefficient of friction (COF) for any floor tile you buy. OSHA has requirements for what COF is appropriate for various uses (dry and flat or wet and sloped, for example). It wouldn't surprise me if that sort of thing eventually makes it into the residential building code.