Of course, station barriers have other roles.
Now, everybody knows that children on train are a nightmare to your standard, grumpy, entitled commuter. Right? So, barriers can be deployed to make stations as hostile an environment as possible to those travelling with children, particularly those in pushchairs.
Want a single wide gate for both entrance and exit, where you have to queue up with everybody with children, luggage, bikes, tickets that don't work or from a station with a broken machine? Want to have to juggle a gurning toddler, a pushchair, some luggage, a sippy cup, a dummy while finding the right combination of tickets for your family group? Want to have to negotiate getting to the other side of the barriers to find the baby changing?
No, well, why would you. Best to buy an oversized MPV and choke up the city instead. And leave the trains to their rightful users, grumpy commuters.