I wouldn't exactly say limp is "the norm", but I think a goodly percentage of guys don't have your problem (I use the word "problem" only because you seem to be perceiving it as such, not because I think there's anything wrong with you).
I myself used to get hard and
quickly, unless I was careful, in my younger days, and even now I often have to order a guy to stop or slow down masturbating me so I don't
before I want to. However I never really had a problem with getting unwanted erections at awkward times. It may have happened once or twice in school class just post-puberty, but not as an adult.