Interesting; I'm a CS prof., where you can sometimes get away with that, but increasingly the expectation is really that you'll be funding several students out of your grant money, and at some schools, funding a portion of your salary. Baseline to get tenure at a research-oriented university seems to be about $500k-$1m of grants during the 6-year assistant position (i.e. enough to fund an average of 2 PhD students per year over that period out of non-TA/dept money).
It could be less in math because there isn't the same "lab" concept, where to be considered a "successful" professor you're supposed to oversee a lab of 3+ (better if it's 5+) PhD students, a post-doc or two, research scientists, etc.?
Yeah, thankfully this lab concept is absent, although it is always good to be advising grad students and postdocs. Most universities have tons of students who need to brush up on mediocre math backgrounds, which makes for a lot of paying work for math grad students.
It could be less in math because there isn't the same "lab" concept, where to be considered a "successful" professor you're supposed to oversee a lab of 3+ (better if it's 5+) PhD students, a post-doc or two, research scientists, etc.?