My kids live out of state so can't guarantee they use them all the time but wife and I do and they did when we were with. I am a believer in freedom and personal choice and put thousands of miles on motorcycles without a helmet, though I encourage their use. Seatbelts though I am adamant about and here's a couple of reasons why.
A few years ago our 22 year old nephew was driving to work in the morning and fell asleep. Rolled his Mom's truck, thrown from truck, shattered a few bones, crushed his face in, several years of rehab and he's just now trying to transition from wheelchair to walker and has permanent brain damage. He will never have the life he used to have being a fishing buddy of mine, a true hunter, state skeet shooting champ, and hiked the mountains of CO for elk with his Dad.
A week ago our 19 year old niece was just driving a few miles home from her friends. Swerved for deer, lost control, took on a tree sliding sideways right into a tree. Busted leg in two places, broke arm, shattered orbital bones around eye, and suffered brain trauma. How bad she is going to be and how long and complete her recovery is now just beginning to be evaluated. She is just now beginning to recognize people.
Both of these crashes were within a few miles of their homes and why wear a seatbelt for that couple of miles? How things would have been if they'd have been belted is always open to question but I'm sure either would change some bruised or broken ribs from the belt versus the recovery they're going through.
I believe in choice as adults but I will harp on seatbelts from youth on hoping it carries into adulthood.