You're right to point out that DUIs are a US issue, but Apple being asked to remove an app that may aid someone to avoid a law-enforcement measure may one day affect me here in the UK too if such a request were ever made about a UK enforcement measure.
I understand the concerns people have about a nanny state. There is a huge debate in the UK about speed cameras that has many parallels to this. What was striking was people arguing that they were just a money-making mechanism, when only those breaking the law were ever fined.
My feelings on the matter are simply that whilst it is clear that these measures should not be abused by the authorities as they appear to be on occasion, they are still ultimately there to prevent crime. I suppose ultimately there is no perfect solution. I can see both sides and I agree that these DUIs seem to be unAmerican (if that is a word) but we are talking about the principle of companies like Apple distributing apps that allow people to avoid a law-enforcement measure. I think that specific principle is wrong and these apps shouldn't be encouraged.
But the speed cameras and average speed gates haven't made a significant difference in recorded safety, they just make a difference in recorded citations and associated fines. Not to mention since you parliament got wise to the police fundraising they cut off the police departments take of the proceeds and now revenue from the cameras is significantly down! Why? My guess is the police's motivation to press the issue went down so fewer tickets are going out. But curiously nobody is saying the accident rates are going up!