The established big boys could afford to not do the annual RPI + x% increase, but they choose not to as a business decision.
I think the best answer I would give to your question is the companies are in different places in terms of their development.
BT, VM etc. are established big known brands who will want to maximise profit for their shareholders, the long contract lock in combined with these increases facilitates that.
Whilst someone like Yayzi, they will want to maximise growth, so will forego profit per user to try and achieve that. I agree with earlier replies many of the altnets seem to be planning to be flipped.
There is providers on the middle ground like AAISP, Acquiss and Idnet who wont increases prices during contract. (or in AAISPs case even out of contract), but they may have higher prices as a starting point.
Edited by Chrysalis (Wed 29-May-24 18:01:53)