IIRC this is already happening with a small operator in the Pacific flying Islanders.
I've been asked to stand on the scales once when travelling on a DHC8 from a marginal runway, the take off was with power set against the brakes.
Mum and Dad told me back in the day (1950s) they used to weigh passengers for a Dragon Rapide service Southampton - Jersey. But that was all about weight and balance, not to enable them to charge people more per kg - actually in those days stones and pounds. When the operation moved to Blackbushe and used Dakotas to the Channel Islands they didn't have to weigh the pax.