Hydro jetting can damage cast iron pipe, but mainly when the pipe is already weakened. Sound cast iron handles jetting at the right pressure; cast iron thinned by rust or cracked at the joints can be worsened by a full pressure blast. That is why a camera inspection comes first and decides whether to jet and at what pressure.
Age alone does not tell you the pipe is fragile. A camera inspection shows the wall condition, cracks, separated joints and any sags, and that is what sets a safe pressure rather than a guess from the year the house was built. Newer cast iron, PVC and ABS take standard pressure well; severely corroded cast iron, cracked pipe and collapsed clay may not take full pressure at all.
When the camera shows pipe that is too far gone to jet safely, cleaning is not the answer. Cabling or snaking is the gentler way to open a fragile line, and a line that leaks or has lost wall needs repair such as pipe lining rather than another cleaning. Jetting is for buildup in a pipe that still has its structure.
No pressure number is automatically safe for old cast iron. Safety depends on the wall thickness and condition the camera finds, not on the pipe’s age, so the same line might be jetted at reduced pressure or not at all. The broader question of whether hydro jetting damages pipes covers the other materials the same way.