I agree, I had a conversation like this with my DD at the start of the summer and said she is old enough now to understand that relationships are reciprocal
I think teenagers take a lot - lifts, money, help in organising their lives.
I don't want to feel used, and 16 is old enough to understand you have to make an effort to have a relationship beyond just taking resources.
So I was pretty explicit about what the expectations were - show up to grandparents birthdays and be pleasant and engage, spend a small amount of time engaging with (much) younger sibling, come in and say hi and talk for 5 mins when you get home, don't just disappear. We all have to do things we don't want to do sometimes.
All relationships take effort and teenagers ought to start understanding that they can't just take and expect endlessly without putting effort into maintaining relationships
Being very clear about expectations was effective, but it felt pretty crummy spelling out all the things they used to want to spend time doing.
We do now have lunch together once a week, it's nice. Significantly more effort is made. A boundary needed drawing I think.
I do agree though, it is upsetting when you compare the before/after teenage years.
I dread to think what comes next.