I've seen it first-hand. The old lugged and bonded Trek frames are much more resistant to this than welded frames, because that construction method minimises th

I've seen it first-hand. The old lugged and bonded Trek frames are much more resistant to this than welded frames, because that construction method minimises the stress concentrations that initiate macro cracks. E-bikes are probably more vulnerable, partly because the structure is compromised to allow for battery installation and wiring, but mainly because there's a bunch of extra torque going through the chainstays. https://www.sheldonbrown.com/rinard/frame_fatigue_test.htm https://www.sheldonbrown.com/rinard/frame_fatigue_test.htm An aluminium frame used in all weathers is vulnerable to galvanic corrosion. Aluminium is less noble than steel, so steel fasteners will rot out aluminium threads. In a perfect world this would be prevented by a suitable assembly grease, but a delivery bike being used through winter in London or New York is about as far from a perfect world as you could imagine. There's salt on the roads, the bike never gets a chance to fully dry out, so any amount of aluminium-to-steel contact is going to lead to very rapid corrosion.