[PSZD]

Working at a large brown shipping company, I've never seen anyone go out of their way to mistreat packages marked as fragile (or anyone talk about doing it).

That said, it's policy not to treat packages marked 'fragile' differently. Boxes get reused a lot, and a sticker like that has very little correlation with it actually being fragile. (60lb box of bolts? Fragile! 2' by 4' mirror that shatters from a 1 ft drop? Not fragile!)

For bicycles in particular, the issue IMO is that they're typically packed terribly, while being large and awkward enough to be handled with all the other large and heavy (70-150 lbs) stuff.

Damages will occur, it's just a matter of statistical frequency at a scale of 20 million packages per day handled by 100,000+ employees. Frequently, the damage won't even be discovered until delivery, and then there's no easy way to attribute the damage properly. That means aside from particularly egregious stuff where it's obvious you screwed up (say, laying a 55" TV flat and dropping a 30 lb box on it) you have to go way up the management chain to find anyone who cares. At a lower level, easily measured metrics like process rate are far more important.

If everyone in management you ever interacted with only measured your performance by LOC written, how much time would you spend refactoring?