Moriarty opened the ticket and wrote:

r20635
For some reason, the scenario editors place "many random X" (where x is either towns or industry) is tied to to the "new game" settings "no. of towns", "no of industries".

For example, if I click "build" for many industries in the scenario editor, it simply won't place a single industry if "no. of industries" in the newgame dialog is set on "none". If I change this setting, the number created is dependent on what the new setting is at.

I would instead suggest that a fixed (and very low) number be randomly place. If the user wants more, it's easy to click it a few more times, but removing items (especially from a large map) is much more time consuming.
Semi-relatedly tree's plant too many when you click "random trees". If I want sparse tree cover there's no way to do it except manually. Again, it's easy to click "random trees" many times if you want less-sparseness.

Reported version: trunk
Operating system: All

This issue was imported from FlySpray: https://bugs.openttd.org/task/4094