SIL and her husband have never been abroad, they are in their early 50s. They haven't ever been to Scotland or Ireland either. They have, in the 25 years i've known them, had two holidays, both at the same Center Parcs with SIL's parents.
Not because they can't afford it, but because they have an incredibly small comfort circle. They very rarely leave the town where they both grew up, live and work. An expedition to the nearest city is a major undertaking which only happens on very special occasions. They have no interest in going places, or seeing things. They are scared and intimidated by anything different or foreign and have very narrow horizons in other ways too - very plain food preferences, don't like trying anything new or experiencing anything new.
Up to them of course but it makes for very tedious conversations when they have nothing to talk about as they don't DO anything apart from going to the same places, eating the same things, seeing the same people, watching the same things on telly..... yawn.
I also think the environmental thing is a total red herring. This is something which has only been a concern in the last 10 -15 years. Someone in their 40s or 50s can't use that as an excuse.
I love travelling, love seeing places and doing different things, whether that's in the UK or overseas. I find people who have no interest in exploring their world very tedious, narrow minded and insular.