I wonder how many power pilots do check the ASI ion the takeoff run Also why is it not a check in a glider?
Yep, I do, along with ensuring it's developing the expected number of RPM.
However, in a glider it's a little more tricky - you're bouncing along what usually feels like a ploughed field - the wheel is 6 inches under your butt, trying to fly in formation behind the tug on the end of a piece of string. You'll become airborne a long while before the tug, then you have to fly 2ft off the ground, in formation (remembering in a crosswind you'll have to counter drift well 'cos the tug is still attached to the floor..) I'm not saying it's not possible, or you shouldn't but it's a very head out occupation, and taking a good look is less practical.
Abort options: Pull the yellow knob (tow release) and park it; same as a cable break. Land ahead, make a low level turn and land across the field, over the hedge and into the next, or complete a truncated circuit / turnback. In many ways the glider's got a lot more options; you can do more with less height.