Aircraft Technician found missing panel on engine thrust reverser during pre-departure walk around.

Narrative

During routine ETOPS check found door/panel on #1 engine inboard thrust reverser upper hinge beam aft small door missing.Door was missing from panel. [Document] does not allow mid or aft access doors to be missing.There have been countless number of findings/damages/missing parts etc which causes un-necessary delays and sometimes cancellation. A lot of these can be prevented when a qualified technician does a walk around in a timely fashion. Allow all line mechanics to do general walkarounds on all flights..not just on ETOPS flights or scheduled service checks. mechanics should be allowed to do a general walk around on all through flights that come in and out of there assigned gates. Letter says no more walkarounds due to staffing levels at ZZZ....ok now staffing levels are back to normal..we have hired 100s of new mechanics..also see updated and extensive ramp agent walk around below....why pay a mechanic to do a walk around when you can pay a ramp agent to do it and save lots of money.....this is not safe because ramp agents do not know what they are looking at; they are not trained; they are not qualified.........not trying to rant here..........just trying to emphasize on the importance of safety in this industry....its all about customer and aircraft safety.......... Company X is all about safety -- so what happened to safety now?