Robin Hanson from overcomingbias.com complains that physicists get more respek than economists.
It seems to me that the arguments that sprung up around this are a good example of your original point. Do you think there would have been as much argument if a physicist had said what you said? As far as I understand it your claim was very narrow and specific. There is a consensus that raising the minimum wage has a negative effect on employment rates. People automatically interpret this as you saying that therefore one should not raise the minimum wage, and that is a whole different question, involving many variables beside the employment rate that economists don’t agree on. It reminds me a lot of the controversy around the claim that abortion has decreased the crime rate. You can be aware of this phenomenon and still not be in favour of abortion.
I don’t really think this is a difference between economists and physicists though. I think that no scientist is given much credence when their theories disagree with peoples opinions. Theoretical physicsists have the advantage of rarely coming up with theories that challenge normal peoples opinions, so they just say “that’s cool”. People argue and look for balancing opinions when they perceive a scientific theory as challenging their beliefs (whether in fact it actually does or not). Look at evolution.
The difference is between normal speech and scientific speech. In normal speech, mentioning a benefit of a strategy is usually done by an adherent to the strategy and with the sole purpose of promoting it. Policy decisions are separate from scientific discourse, and although they should be influenced by them, often a group of people will decide that despite all the tangible benefits demonstrated by science, there are intangible costs that outweigh them. They don’t have to be logical in a strict sense of the word.
Perhaps the best way is to put a disclaimer on every example of scientific speech. Something that shows that while what you are saying is considered by you to have been demonstrated empirically, positive findings do not necessarily indicate a personal endorsment of any policy nor do negative results necessarily indicate that a policy should not be persued.
So anyway, back to your original point, I don’t think anyone respects physicists more than economists, it’s just they disagree with them less often.