why is it not accepting "we're seeing him there"? I've had this problem with continuous/present this whole topic
I think a difference (yes, another one!) is developing between British English and American English (and maybe other types of English, too). British English uses the present continuous to show that something is going on at the present moment, and perhaps is interrupting another action. "I can't come because I am watching paint dry". A habitual activity is usually simple past in the UK. "I swim" (regularly) is different from "I am swimming" (at the moment).
"I love lemonade" = I always love lemonade (it's what I do). "I'm loving it", that well known advertising jingle, irritates British English speakers because it suggests one is currently in the throes of delight, in "the moment" as it were. What is required is "I love it" (I like this stuff all the time). A dubious assertion at the best of times...
We see him does not mean the same as we are seeing him.
You said a habitual activity is usually simple past in the UK, but you meant simple present, surely.