• By design.

      Bitcoin has pretty much no incentive to make the transactions efficient. The load is distributed to other people (their customers), and their biggest customers have a perverse incentive to want the transactions to be as inefficient as possible in order to discourage competition.

      Vista et al have to pay for their own transactions, so keeping it light is simple cost savings and totally rational.

      • ethereum moved to proof of stake sometime back. BTC and I think a few other (very) minor cryptos still use proof of work which is where the significant power usage goes. Not something I track but I believe the vast majority of non-BTC cyptos are proof of stake or something not proof of work anyway and BTC is the only one that uses proof of work and is used at all. That might not exactly be technically correct but it is in the practical realm.