So I'm trying to get my sims to use the changing table for babies/toddlers instead of the change diaper interaction. The changing table "Change Clothes" interaction is set to Autonomous but they are still refusing to use it. I changed the standard "Change Diaper" interaction to not be Autonomous and they stopped doing that but now instead they just aren't changing the diaper and ignoring it. Does anyone have any idea what the issue is?

I'm not sure there actually is a solution for autonomy on that item. But you might try also using Retuner to increase the amount of motive relief (perhaps Fun?) that it advertises to sims around it.

The problem with making the standard change diaper interaction not autonomous is that other sim households with babies, to the extent that they are animated/being simulated, probably won't change their babies' diapers either.

Hmm was playing with it some more by retuning the values and they are still by default doing the normal one or putting the toddler/baby in the crib then using the "take care of" interaction to change the diaper even when the changing table is right there and has higher overall motive reliefs. I'll have to keep fiddling to see if I can find any other/better solution.