I was thinking about this today on the train
For me I think it is the simple shoe lace.
When I started wear boots it wasn't uncommon to wear out a set of bootlaces a day in rough terrain when not wearing gaiters and not all of us could afford gaiters [ even the army jungle gaiters were expensive when at secondary school and no youth allowance] and now I don't think I have worn out any laces in a normal year
I bought a pair of the super expensive Tobby boot laces in England in 1979 and while worn they still aren't worn out
Funny tho because I still carry a couple of pair of spare boot laces