If anyone can't solo until 80 hours they should have given up long before. That is a heinous time to solo and implies zero aptitude.
Or lack of regular flying, as has been stated.
Or poor instruction, leading to loss of confidence and/or a need to change instructor and/or flying school.
Or problems in a particular area that aren't picked up and dealt with.
Or a school giving up on you, but taking your money, when a change of instructor or similar might sort things out.
Or....a whole host of other things I haven't experienced or heard of or thought of.
Cheers,
Whirly (48 hours to f/w first solo, 90 hours to PPL, marginally better with rotary, instructor who never gives up on slow learners since rate of learning proves bugger all)