Way back when I held an instructor rating, I let TIF students take off, if the conditions were suitable (if they werent we tried to talk them into a TIF on a day that was going to be nice).
As others said, the instructor is a salesman on a TIF.
I've even sat in the RHS when taking family/friends flying (if it was nice wx) and let whoever is in the LHS takeoff and fly as many of us know, basic vfr flying isn't rocket surgery.