Our college DD uses our Netflix and Hulu (legally), and shares the Prime that DH and I have. I can’t imagine not using Amazon only a time or two a year! DH does most of his Christmas shopping on it, I send stuff to DD all the time-in the last couple of weeks-a necklace, dress, curlers, and several textbooks at the start of the semester )WAY cheaper than other book sources). We have a grandfathered cell plan so DD is on that too.
My ex kept our DD on is insurance till she aged out, and on his cell plan until he started using it like a club (I pay, you call/answer when I say so). She got her own phone and a new number and controls her own calls, being 27 and all.