Having served on a parish council there can certainly be a technology challenge for some.
There are services which will do the work - https://cuttlefish.com/local-councils/ - https://www.parishcouncil.net - are two of many. These have their drawbacks, may not provide exportable data so locking the council in. Some will allow direct access, some require that any new content be sent to them and they upload it.
Some councils will own their domain name, some will not. Then there is the email issue and many will use a gmail / hotmail address.
Cost, especially these days, is also a factor.
I don't see it as a bad thing to have so much variety though.
One thing that British local government definitely is NOT, is consistent. 500 years of continuous monarchic rule means the backbone of the State is a rickety Rube Goldberg machine, riddled with absurdities and obsolete entities that change every few miles. What you mention is the tip of an iceberg as big as Greenland, where every other town or region is administered in fundamentally different ways for no particularly good reason beyond "that's how it's always been".
For all their centralist instincts, the Westminster classes fundamentally don't care about how the provinces go about their business, as long as they keep paying into London and act adequately subservient whenever the Southern classes come knocking. So we have to live with constitutional aberrations like Cornwall and Lancaster.