No offense meant.
I suspect, though, that you notice it more about the US because you are just visiting, and less about the UK because you're from there.
In the US, most houses don't have flags, and most flags are on public buildings. I don't even know what you're referring to about ice cream cone holders, but I wouldn't be surprised if some brands used the stars and stripes for marketing purposes. It's pretty popular for people to display flags and nationality on their cars -- those living in the US who are from other countries or the children of immigrants will often stick a flag-sticker or symbol of their home country there.
I don't see what is so bad about flying a flag anyhow. Seems to some of you as if someone who puts a flag outside their house is deserving of some scorn.
"I hate to advocate drugs, alcohol, violence, or insanity to anyone, but they've always worked for me". Hunter S. Thompson.