The biggest contributor would be power steering in the seventies in most cars was overpowered steering where you loose sensitivity to the road. Additionall these units were not speed sensitive (need less power assist while moving than stationary.) Bias ply tires, backlash on many steering components and mushy rubber bushings also multiply this sloppiness.

Several convert to rack and pinion type steering boxes for better sensitivity to the road. If you have the muscle go with manual steering.

Newer designs design for road feel, control, speed sensitivity, backlash/mechanical tolerances.

Eric