Hotels/Airports with IPv6

Limited municipal budgets is all I can say.
IPv6 has a cost, and if they can put it off
till later then that's often good politics.

IPv4 has a cost as well. May as well just go
IPv6-only from day one and not pay the IPv4
tax at all.

The cost difference between providing IPv6 +
IPv4 or just IPv4 from day 1 should be zero.
There should be no re-tooling. You just
select products that support both initially.
It's not like products that support both are
more expensive all other things being equal.