Personally, I don't believe in any conspiracy or anything, I think that it is just a matter of business cases...
If you're a 'smallish' town looking to upgrade your comms, migrating to new technology might make sense, especially if someone out there has already put up an infrastructure which you can piggy-back on. If you're a big city with quite an investment in your own infrastructure already, decomissioning the old stuff, especially it it works OK, is probably not worth the $$$. Ottawa was already looking at major investment into comms to handle all of the city departments, so making the move was a no-brainer.
This is just a matter of 'outsourcing' the infrastructure in the case of smaller towns. Can't really fault them.
Cheers,
Boomboy64