What is so hard about believing that a person died from too much of mixed prescription/over the counter med's in their body? Why must it be that someone is "trying" or "covering" something up?

If you want to talk about covering something up to make it seem "accidental" then how come hollywood didn't do that with River Phoenix, or even the one other actor that just recently passed away? (forgot his name) My uncle passed away few years back from similar situation like Heath's. He had too much of med's mixed with multiple other med's in his system that caused his death.
This happens to hundreds and hundreds of people each year. Like someone said earlier...when a doctor asks if you are taking any other drugs, you need to be honest and tell them, so that they know what to give you or what
not to give you. Doctors don't want to be responsible for your death. Doctors want to help you get well...not kill you.