I picked a totally arbitrary number. If we sat down for more than the 30s it took me to make this reasonable sounding number up, I'm sure we could find a satisfactory system :)

Any satisfactory system will be alterable by

(a) inflationary practices

(b) those scheming to take advantage of loopholes

in 10 or less years.

Unless you (a) index it to inflation and (b) make an attempt to close loopholes, rather than surrendering at the starting line ^_^

I like your optimism, but I've failed to witness a law that has never been twisted into some gross contorted display of what it was normally used for at least once.

So long as the harm caused by those taking advantage of it is less than the good created by the change, it should still be put in place.

Texas in so many ways scares me, but the fact that many of their laws have expirations actually makes sense.