As a tester, it is your job to tell others what you need in order to do your job properly. A tester is largely affected by the choices made by management and programmers. If other stakeholders are unclear about their plans or design a product which is hard to test, then this will affect your test plan. I’ts not that they do not understand or care about testing and software quality. They probably just do not understand what impact their actions can have on the test process. An important part of testing is to explain testing to other stakeholders.
Your explanations about testing are like a flu vaccine, healthy and not painful, but the effect wears off, so you have to do it over and over again.