Jonathan, I respectfully disagree with your other countries theory.
I have fought with Brits over which Red, White, and Blue flag is better ... and they love to fight playfully
I have been to over 14 separate European countries and they re proud of who they are and can tell you quick what their flag stands for. Many of those countries I have spent time in at length. Now East Germany (DDR) was a whole other animal on it's own. Countries like Poland, Serbia, Croatia, Romania,Albania, Macedonia, Germany, Switzerland, Lichtenstein, Belgium, and the Netherlands ... big flaggers.
Ask a Mexican about their flag. They fly it in everywhere and many tattoos of the flag. Same for PR. But dare not compare the two or you are asking for a fight. Most Latino based countries are this way. Lest not forget Caribbean countries. Pride is in the forefront.
Canadians love to fly their flag in all provinces.
Between Japan, Korea, Taiwan, and so on. Pride is what I witnessed.
Now we go to India and Pakistan. They fight for their flags. Most Middle Eastern countries I have been to do not shy away from their flags.
Africa is a bit different but say Nigeria, South Africa, and Egypt.
American left is unique as they paint the flag as a symbol of hate and repression. Heck, they even say it unabashedly.
I understand you are a young man so your experience does not give you a good base. I hope i just added to that base.