The tea bags are huge catering type things one per pot. The pots are all identical (whoever has the contract must be making 'pots' of an entirely different kind), because of this its easy to use them for coffee on the first round, then tea second round. It's well nigh impossible to rinse them out properly - we can invent a remarkable machine to fly anywhere but it appears beyond the wit of man (and it must have been a man), to invent a sink that drains properly.
Catering are meant to rotate the pots after every flight - but the same old pots go round and round sector after sector, getting grubbier and grubbier.
Have I put you off yet ?
finally, in order to serve 300 + pax quickly you can't wait for the tea to 'mast' as my old granny used to say. You simply swirll the bag about with a spoon, haul it out and plop it into a plastic glass and using a second glass squeeze the bag's soggy content back into the pot.
There, now you know.
Abbracadabbra abbracadee, make this coffee into tea.