Doesn't seem that unreasonable to me. If you accept the notion that fines are designed to incentivize a behavioral change, then, likely it takes a fine of this size to deter the particular (repeat offender) driver.
It's doesn't matter what the speed limit is, going 85mph through a village is a serious matter (unless you're in the mille miglia in 1958) and threatens life/limb. If you've driven a lot in Europe then you know that the speed limits tend to be quite high through the villages, unlike here in the US where we have a lot of 25mph zones in congested areas. European drivers tend to drive below the speed limit if conditions warrant it, whereas here we all do the speed limit or more most of the time.
If you want to go really fast, do it on a track where everyone knows and understands and accepts the risks. If you're being really stupid then chances are still pretty good that might kill someone other than yourself unfortunately.....