And those are just capital ships, UK had 100+ destroyers and 40 pre-drednoughts. I know it was a different world, and they were in an arms race, but still, it was before the total war started.
The disparity in financial capability for their navies just seems so implausibly disproportionate? Most assuredly France and UK are much more wealthier today, no?
Ship class inflation and economies of scale
Some of the first "destroyers" in the late 19th century were in the 2-400 ton range with 40-70 crew. By the start of ww1 a 1000 ton destroyer would not be out of place in the Royal Navy. Today the most modern US destroyer is closer to 16,000 tons with a crew of 180.
By weight alone a modern destroyer is not that much lighter than the HMS dreadnaught (18,000 tons), and heavier than those pre-drednoughts. Size and weight adds obvious cost but the massive addition of electronics and modern "smart" weaponry makes the design, conscruction and operation of a single modern destroyer very expensive. The plus side is all that technology means a single ship has far greater capabilities than dozens of ww1 era vessels.
A similar amount of ship inflation has occoured in all other ship classes, exspecially aircraft carriers that absolutely dwarf their ww2 counterparts.
Now economies of scale.
When you are building 30 of the same class of ship the reserach and development cost is spread across 30 vessels making the individual unit cost lower. Spare parts manufacturing, transport logisitics and crew training becomes much, much easier when dealing with multiple ships.
For example the patrol boats of the australian navy have 21 crews for 13 boats. This means mass training is possible while the boats can be in operation constantly while still allowing crew rest and recovery.
But when dealing with one or two vessels of the same class you need to provide training effectively one on one. And To keep that vessel constantly operational you need far more reserve personel than if you had a larger number of identical ships.