yep
city wants to make sure that they get their tax money
errr I mean keep their citizens safe
errr I mean keep the zoning laws updated

most of it is tax money, some of it is the holes are deep enough (some cities) and that tis' not too tall. 6' is considered ok everywhere I know of, but over that is a no no.

Most fencing places are pretty price competative. It's a very low margin business. You'll have to figure in the removal of the fence also, that's more money too. Call around, ask your neighbors, etc. With the housing market slowing, most of these fencing places are probably looking for work.