some remarks
- the usage of the word "holland" is incorrect, as "holland" is just a part of "the netherlands", situated in the west and northwestern part of the netherlands. this area can be divided into two provinces: zuid-holland and noord-holland, both above the river rhine and maas.
in 1944 only the southern and south-western part of the netherlands was liberated: the provinces of zuid-limburg, noord-brabant and zeeland. "holland" was only liberated in the spring of 1945. so this diorama cannot be situated in "holland" in 1944, it can be in "the netherlands" in 1944.
- i agree with mr den bakker the windmill is most likely used to control the waterlevel in a "polder". as this windmill is not that high, it's most likely situated out of the vicinity of a village or town, so at the edge of a polder. (windmills built inside a town or village were higher, to catch enough wind. these windmills usually have an "omloop", a kind of catwalk around the windmill. these types of windmills are called "stellingmolens" (sorry, cannot find the english word)
big parts of the provinces noord-brabant and zuid-limburg are above sea-level, only "zeeland" is below sea-level, a bigger need for watermills in zeeland
- the vehicles are american, and americans only fought for a very short time in the netherlands, as this sector of the front was allocated to british and canadian troops.
so the diorama is generic, and could be plausible if the title was changed into "netherlands 1944". if you want to place it in a certain area, zeeland is your best option, but zeeland was liberated by canadians, british and polish forces
attached a picture of a "stellingmolen" from my hometown wateringen (close to den haag). the reason the miller built such a high windmill is because he had an argument with his neighbour and at a given time he was so angry that he said "i will build a windmill that high so i can piss into your chimney".... rembrandt van rijn's family used to own a windmill in wateringen, but not this one