Of course it all depends on the individual and the relationship between people, but as a Brit, I would say that we do tend to be somewhat more protective of our opinions and beliefs than in other cultures - especially when it comes to politics. It is not uncommon for people from the same family to prefer to keep private, their decision to vote for one group or another, if only to avoid unnecessary arguments. So it is safer to be cautious in such discussions and avoid direct questions. The same goes for questions about money : I would never ask someone how much they earned, for example. It might well make the other person feel uncomfortable - as if they were being judged in some way. In many other cultures of course, such questions are common and perfectly acceptable...

In the U.S., people generally limit political conversations to people they know to be like-minded. It is dangerous to do otherwise. Even if people do answer your questions about politics, the answers they give you may very well not be truthful. They often tell you what they think you want to hear rather than what they actually believe. This is a serious problem especially for polling organizations which find themselves unable to collect useful data because people give answers that are not honest. People lie to the pollsters because they think the pollsters themselves have opinions of their own and do not trust them.