It's a money spinner for the council. They charged me £900 to get the curb dropped outside my last place. Another resident was taken to court for doing his own, had to pick up the court costs and then pay the council over a grand to rectify the work. They replaced his lowered curb with one that was of no better construction.
The council charge because
1: It has to be done to a set standard
2: Because of 1, it has to be done by a company certified/known to do it properly.
3: Whoever does it has to have the right insurance.
4: It has to be maintained once done - dropping the kerb results in extra wear on the pavement between the road and the drive.
5: The change has to be logged with all the correct authorities - highways, planning etc.
Yes some people might be able to do it themselves, but there are many others (including companies) who wouldn't do a proper job and might well damage the surrounding area/make it unsafe, and the council wouldn't know about it.
IIRC you can get permission to drop the kerb and then contract people to do it for you yourself, but it generally ends up costing more.
Re the original post, I quite like the idea of the posts, grass verges (with raised kerbs) are there to allow for some natural drainage, improve the look of the area and give some open space.
People driving their cars over the kurb damage the kerb considerably over time (the kerb isn't meant to take that repeatedly, and is not anchored for it), makes the area look messy and seriously damages the grass.
There are a couple of idiots near me who do it from time to time, and there are great muddy ruts in the grass because of it (just one 4x4 doing it this weekend left noticeable damage on on
trip).
I bet it costs more putting in Bollards than it does to drop a Curb.
Probably a lot less, pillers can cost less than £100 bought in bulk, then you've just got the cost of 2 guys for a few hours (they can probably do a fair number of them in a single day).