The more likely explanation is that your teenagers have some public transportation available, so they can go somewhere if they want to.
Public transportation was non existent for the parent 30 years ago. If you look at cities all around the world, most tubes and overground lines were constructed in the past few decades.
The quality of public transportation in my city has not changed in a relevant way in the past 20 years. My teenager spends way more time at home than I used to (there's the old fart!). The internet is definitely a more relevant change.
