much - very much, many - very many?

Question

In case of uncountables, the large amount expressed by much like in

much water, much money, much sand

can be increased by prepending very like in

very much water, very much money, very much sand

But in case of countables, the large amount expressed by many like in

many trees, many people, many children

can not be increased by prepending very? So, the following is wrong?

very many trees, very many people, very many children

Is there a comprehensible explanation for this difference?

And what is/are the correct expression(s) to increase many?

Answer 1

You are mistaken. It is correct to use very to increase many. To me it sounds simply a little redundant and begs the inclusion of more specific information since, as you pointed out, many is used for countables.

For example, the following sentence is grammatically correct:

There are very many trees in the park.

However, in conversation I would then reply:

How many trees are there?

Or perhaps I would inquire as to the variety of the trees.

One can also use great to increase many:

There are a great many trees in the park.

Note the use of the indefinite article "a" with great many.