Why can't bmtc buses have rechargeable cards/QR tickets like namma metro?

I'm pretty sure all of us have gone through this hassle of either not having change/not having the correct amount of change/bus conductors not having change. And in some extreme cases the conductors just kick you out of the bus because you're not carrying cash( happened with me thrice)

I know a lot of you might say ethey have UPI now but that is not solving the problem completely as majority of the conductors are just hesitant to take payments via UPI as they say many folks dupe them and show fake screenshots or say that money got debited and it's still processing and whatnot.

Wouldn't it be easier if we just had physical bmtc bus cards like namma metro cards?? And then we could recharge them via UPI and then just tap on the conductors machine based on the journey?

They could go one step better and have us scan QR codes for the rides(again like namma metro QR tickets) and wouldn't that be much simpler as well??

When one mode of public transport is doing it successfully why not adopt it for other widely used public transports???