I remember Billy Mayfair and his push cart back in 1985-ish at the NCAA championship. It did stand out but made total sense. The game is a devastating wallop to the back.
As far as outlawing them, the anal-retentive are at it again! On what basis could you outlaw a push cart? The same one that allows you to limit number of practice swings, looks at a putt, and on and on? A push cart serves one purpose: to limit strain on the back born of carrying a heavy sack on the shoulders. A double-strap certainly balances the load, but in no way decreases it.
If you have a burr in your saddle about a push-cart, you certainly are too young (or too spiritually constipated) to be legally allowed to have an opinion on anything.