Talk:Trade Cart/@comment-26842175-20150802091408/@comment-87.128.18.178-20180427112935

that's because they use two different models entirely.

My guess is the devs wanted to save a tiny bit of disk space because they assumed nobody would let a loaded cart just stand around, so they didn't give it an idle animation. This makes sense because back then, you had to fit everything on as few CD-ROMs as possible, so tricks like this were done to save space quite often before downloading because common with better internet connections.