Meanwhile we have 2 types of martime helos where the USN manages with 1, 2 types of frigates being built in parallel whereas the USN has just 1. 2 types of fleet oilers vs USN of 1. The US of course being 7 times larger and spending 10 times as much.
There's a lot wrong here...
We have 2 types of helos because it makes sense. The US also has 2 main types of naval helo. MH-60R and MH-60S. Both do different roles and are equipped very differently. The R is not as capable as Merlin HM.2 is at ASW, but it does have an 'adequate' air to surface role. Wildcat with Sea Venom and Martlet will be far superior for ASuW. The MH-60S is primarily used for VERTREP and transport. The MH-60 is a good helo, but its a jack of all trades, master of none. And even then as a cost saving measure the USN had to have 2 different versions. The Canadians have standardised on 1 type...but I don't think anyone is seeing that as a great idea...
Personally, I would have sacked Wildcat off and gone for a marinised AW139M or AW149. More room in the cabin for moving personnel/boarding parties, higher vertrep loads, range and with no folding tail rotor boom, the advantages that Lynx had are no longer there. Probably would have been beneficial to Westland as well. The Army could have got themselves a Scout/Cab far cheaper elsewhere.
The US will also soon have 6 main surface combatants: Zumwalt Class, Ticonderoga Class, Arleigh Burke, FFG(X) (US FREMM) Class, Independence Class LCS and Freedom Class LCS and thats if we ignore the 3 current different AB variants and 1 being built (and there are currently 3 variants of the Flight III's being expected)
The RN currently has 2: Type 45 and Type 23. We'll be moving to 4 in 2027 (as T23 will crossover with T26 and T31). The intention will be 3, if we'd stuck with the original 14 T26 it would have been 2. The USN meanwhile is wedded to 5-6 classes (and within those numerous sub-classes) for the next 20 years (6 unless they retire the Tico's).
The USN will shortly have 2 classes of Oiler, just like the RN, as 14 of the 16 Henry Kaiser Class are single skinned, they're not MARPOL compliant, the US is now building the first 2 John Lewis Class Oiler as replacements. With large numbers of Oilers the USN, like the RFA, is bound to have 2 classes in service for a significant portion of time as previous classes are replaced.