I would be less worried about the blade fragments stabbing me than I would be about tumbling into the ground at high speed if a blade breaks. That is a bigger safety concern here. With loss of one corner, you are a tumbling rock.
I'm not sure I would say often. The no speed limit stretches are much more limited than people outside of the country seem to think, and often are temporarily limited when needed, times of higher traffic, road work, near cities or on/off ramps, weather conditions, etc. It is not as much of a free for all as you make it out to be.
We already have laws that make people responsible if they are speeding and crash and hurt someone, and people still do it. The problem with your logic of "there should be no rule unless someone does something to hurt someone" is that people are not always rational, and once someone is hurt or killed it is too late. It is better to try and discourage the behaviour that hurts someone before it happens, rather than after.
Sure, the standard could be made relatively easily, but how do you go about getting every bank to agree on this standard and update their systems to accommodate it, as well as the 10s of millions of POS terminals in the US alone to be updated, as well as all of the major credit card companies, etc.