Why isn't it "wenigere Menschen"? It is an adjective without a preceding article, so I'd think an -e ending is called for.
I also do not understand why it's not wenigere Menschen. Someone please answer this or DuoLingo should correct the German.
I searched online and found the following explanation: https://german.stackexchange.com/questions/36010/why-is-there-no-declension-for-the-comparative-adjective-weniger
Some adjectives like wenig, etwas, mehr, manch, solch, viel, welch are called as Adjektive mit Nullartikeldeklination
am I alone amongst DL's English natives in saying "Why is fewer people better?"
Both are correct. If you use "is" you're simply referring to "fewer people" as a singular concept, rather than using "are", where you're referring to the people themselves.
Wenige seems to mean both few and fewer, but I don't understand when to use one or the other. I keep getting this wrong, over and over again. HELP!
"weniger" is not in the genitive case. It's in the comparative degree.
When would this phrase be used? Would an example be a group of people discussing how many people to have at a party?
Possibly - but then you might say "the more, the merrier"! Have you ever worked on a committee with so many other people that discussions take ages and nothing ever gets agreed? That might be another example. . .