XMR have a smaller e-commerce universe (on clearnet). Its logic to think they should have bigger market share on those who accept them.
Discussion
XMR users can shop anywhere using an instant swap exchange where they send XMR and the other end receives another coin, this is just a pattern that keeps repeating, the whole crypto and even bitcoin itself is still a niche in the clearnet unless you live in El Salvador so always that a new merchants appears the data is always similar with XMR at the top
plus more merchants would actually increase it even further since the current XMR users would have more places to shop, and new users could learn about XMR and have plenty of options to use it
I don’t understand your point about swaps. Every crypto can do it and (imo) it does not sum to the conversation.
Yes crypto’s are niche but Moreno is even more because (sadly) is restricted from a lot of ramps and commerce (BinacePay, Bitrefill.. and so on).
My point: we can not say Monero is more used because in the few market that accept both, monero users spend more there. I could use another crypto market and compare Bitcoin payments against USDT and say “see bitcoin is more used that USDT”. Maybe it’s true, maybe not. But that does not look like the best measurement.