Taking the hat off indoors/at the table.

Last night my husband and I went out to dinner, and I noticed there were two men in the restaurant who were wearing hats at the table as they ate. (Not judging, merely observing.) One was a cowboy hat, the other a baseball cap. That used to be considered very rude. In fact, wearing a hat indoors was considered rude. There used to be practical reasons for that, but since those reasons don't apply nowadays, nobody cares anymore.