This is a strange interpretation of the statement. I would've assumed that the point being made is similar to that about the tax on cigarettes - the cost of a penalty charge is less significant to a rich person.
In some places the cameras are signaled up to 500m before, and are very visible with yellow reflective stripes. There is often one at the entrance of towns to force drivers to adapt their speeds, and it works.
Then some are clearly placed with malice, it really depends.
> Unless someone can prove a connection that someone poor is more likely to speed, then I don't see how that's true.
I think an issue would be that poor people will drive more. Middle class population will tend to be more urban and rely on public transportation for day to day use, even if they still own a car and may do a few trips during the week.
People in remote areas will be more at the extreme: crazy rich or pretty poor, and the poor in these area will have to drive everywhere to get almost anything, thus being more subject to speed traps. (anecdotaly almost everyone speeds way over the limit, some big highway feel like the autobahn sometimes)
Yes! I don't understand why the government doesn't accept the reality and doesn't (try to) raise the speed limit. Now everyone is speeding and when they see something remotely alike an undercover police car they brake hard, creating very dangerous situations for all people around; you could argue "it's their fault, they're speeding" - yes, but why keep the limit low?
This is why in a lot of european nations on top of the fines you have a point-based system – if you have three points you get your driving license revoked and you will have it revoked for some time and then you have to do some driving tests again.
This actually works quite well in preventing bad behaviour (assuming you have a non corrupt police), but one could argue that it is a much, much worse punishment to the poor again (it can potentially destroy them economically, including the loss of income source etc).
And then:
" solely a revenue-generating measure which takes money from the poor."
Unless someone can prove a connection that someone poor is more likely to speed, then I don't see how that's true. I think the opposite was proven recently, no? That rich people with expensive cars are more likely to disobey traffic laws.