ไป is not only the verb “to go”. Hung on another verb it points the action away from the speaker, where มา points it back — โทรไป is you ringing them, and กลับไป is going back somewhere you are not. ไป … มา wraps a whole round trip. It can also spread something all through — ปวดไปทั้งตัว, aching all over — and doubled, เรียนไปทำงานไป, it is two things at once. And after an adjective it stops being about movement at all and simply means “too”: เผ็ดไป, too spicy.