On one hand it is probably small in comparison, but on the other hand, it seems much more feasible to reuse transit ticket ICs than e.g. food packaging.

Many transit agencies do explicitly incentivize reuse, e.g. by offering cheaper fares using a reloadable contactless card and often charging a deposit for that card.

Even then, many of these systems have been struggling due to the IC shortage, given the low margins these single-use tickets have to operate on. In some Asian countries, including Japan and Malaysia, it was tricky to get a new transit card for several months or even years, even though there is a deposit charge.

I don't know about justifying or rationalising waste by pointing to a greater source of waste.

The question is whether it's negligible compared to good old fashioned paper tickets.