A very warm welcome to you at such a trying time 🙂
I find it always pays to wonder, as a sense of wonder tends to open the mind to a whole variety of possibilities. While I wonder about the cultural differences you mention, in the way of manners (a manner of behaviour), some cultures are very big on pleasantries whereas others not so much. For example, in some cultures people may say 'Thank you very much for having me stay with you'. In other cultures the expression of thanks will be seen in a gift they bring or in the way they help out when it comes to where they're staying or in some other way. In some cultures actions speak louder than words. Forms of self expression may vary greatly amongst different cultures. Whether there's a need for someone to develop pleasantries (please, thank you, shaking hands, bowing with respect etc) is a whole other story. Btw, I discovered in my sister-in-law's culture there is no saying 'It was nice to meet you. I look forward to seeing you again'. The enjoyment experienced throughout the visit expresses that already. I suppose you could say the words are just fluffy pleasantries.
When it comes to people's needs and likes, everyone's different. While your husband never felt the need to take a day off work to show his cousin around, you felt the need to show your brother around and went with that feeling. It's a shame your husband spoiled that feeling which involved that special day off with your bro. Some lunch, a bit of sight seeing, some catching up and some laughs etc can be good for the soul. Sometimes you gotta serve the soul. It's nice to give special people in our life special treatment on occasion, something that also serves the soul.
Of course, people can be born into the same culture but be raised differently. While one person may be raised to wash the dishes while being a guest, others may be raised to see a guest as someone who shouldn't have to wash the dishes or wash them on their first night into town. All depends on how we're raised. While we can have some basic and healthy standards in our own home, a whole set of high standards set by a single person can make for a stressful environment. I suppose a question worth asking is 'Are the standards I'm being held to reasonable or extremely high?'. If they're extremely high, that would be called a dictatorship. Been there, done that, and it just about did my head in. In a dictatorship, you can't be your true self and that just becomes depressing.
Hope you enjoy your time together with your brother. If you focus more on the joy, joy is what you'll feel the most 😊
