Verb patterns

I use Cambridge grammar for improving my english grammar and vocabulary and I found something I have problems with ... It's about verb + infinitive without "to" and it's mentioned that only "let" and "make" are ones which are followed with infinitive without "to" and then, somewhere else on the internet I find "help" as the one of the representer from this group of verbs . And they gave an example:

I´ll help you do it.

I mean, I don't say that I would even notice if someone might said it like it is, but I'm pretty sure that I would say "I'll help you TO do it"

So what's the catch?