Do you have any proof for that - I don't want to see it in detail, but I cannot remember a single incidence where my mail was just silently eaten by google? But I agree with what you said implicitly: gmail should let users chose between "move to spam", "only flag as spam" and "simply delete"; I share your pain of having to go through the spam-folder to find the one mis-classified mail once a month.

EDIT: I have had many user reports about this but when checking mail server logs I always could pin-point the problem at either the local server config or being caught in some "you are evil" classification - the latter much more time intensive to fix....)