Being 80 wouldn’t explain it. My 80+ aunt with severe arthritis (as in having had multiple surgeries on her feet and hands) managed two stairs up and down several times a day with no complaints. She considered it good excercise and saw it as one thing that keept her on her feet.
Exactly how much groceries do people have? I currently live two stairs up from the ground floor as I have lived for more than 15 years. It has honestly never even crossed my mind that carrying up groceries could ever be a problem.
https://en.m.wikipedia.org/wiki/MOS_Technology_6502