I have been using IPv6 for years on my mobile plan, so anecdata supports your hypothesis. But it's not only corporate. IPv6 only lit up at home (Verizon Fios)

I have been using IPv6 for years on my mobile plan, so anecdata supports your hypothesis. But it's not only corporate. IPv6 only lit up at home (Verizon Fios) for me maybe 1 month ago. There are also likely very few people with RA enabled, even if their infrastructure supports it.