Is there a good reason why I can use a polite form before から but not before ので?


Does anybody know why - historically, etymologically or logically - one can
use polite forms (e.g. -ます) in causal subordinate clauses before から, while one
must use the plain form before ので?




As you can see in the linked post, and Chocolate and Bjorn's comment - you
totally can use ので and から after the ~ます form of a verb.

When I lived in Japan I heard people say, `行きますから` and `行きますので`

If you want to know the difference, you can check out [This website ~ Kara vs
Node](http://selftaughtjapanese.com/2015/10/29/a-tale-of-two-japanese-because-
words-node-%EF%BC%88%E3%81%AE%E3%81%A7%EF%BC%89vs-
kara-%EF%BC%88%E3%81%8B%E3%82%89%EF%BC%89/%22%E3%81%8B%E3%82%89vs%20%E3%81%AE%E3%81%A7%22),
it does a great job of explaining. But a basic difference is that から is less
formal than ので.

