Are you saying there are network engineers/management at ISPs who don't believe IPv6 is an imperative? As someone who in a former life worked inside large ISPs on the networking side I can tell you that that view would be quite rare. What would be the politics exactly?
Most ISPs run Juniper and Cisco gear in their core, both of these have have been capable of routing v6 for well over a decade now. Additionally if you are running older gear you would have hit the 512K route TCAM limit years ago.[1]
None of this would have anything to do with existing support contracts either. You would be pretty hard-pressed to find a rev of JunOS or IOS/NXOS that didn't support v6.
It's actually much more efficient to route v6 than v4. The global IPv4 table 719K prefixes now while IPv6 has 52K See:
http://www.cidr-report.org/as2.0/
and
http://www.cidr-report.org/v6/as2.0/
Lastly the fee schedule for IPv6 allocations from RIRs are not cost prohibitive for an ISP. Using ARIN as an example here:
https://www.arin.net/fees/fee_schedule.html
[1] https://blogs.cisco.com/sp/global-internet-routing-table-rea...