First of all, is £3 actually "far higher" than fares "typically" would be?Because the word cap is meaningless if the cap is far higher than a typical single fare would be anyway (certainly within urban areas). It's like announcing that there'll be a £1000 cap on rail fares when the highest rail fare is nowhere near that amount!
Secondly, even if it were the cap would still be, by definition, a cap.
It's basic maths - if you put the standard bus single fare up from £2 to £3 that's a fare rise of 50%!
I don't think anyone is disputing that £3 is 50% higher than £2. What is being disputed is your spurious claim that a cap of £3 is somehow not a cap.
Also you are contradicting yourself if you are claiming both that £3 is "far more" than a "typical" fare and that increasing the cap from £2 to £3 would be a 50% increase in fares. If £3 really is "far more" than a "typical" fare then a change from £2 to the "typical" fare would be far less than a 50% rise. That is, to use your own words, basic maths.