People who are underaged are not meant to gamble, possibly children below the age of 18 years as stated in the terms and conditions of many gambling platforms, but it is not actually working because their is no enforcement of this law. Today in many countries, underaged people do gamble, both online, and in shops, but if the law is enforced, and children who are underaged are punished for gambling, children who are underaged will entertain fear , and possibly desist from gambling.
Betting companies appears in front of jerseys as a way of promoting the betting companies, and not for children who are underage to engage in gambling, and honestly enforcement is the only strategy I think can solve this problem, and not prohibiting teams from promoting betting companies.
People usually under-estimate the intelligence of teens and children when comes to bypassing obstacles which are supposed to prevent them from gambling, smoking or even consuming alcohol.
I remember when I was a teen, there were some guys of my age which smoked and even gambled/played cards in our school.
If someone (teens included) actually want to gamble, they will find a way to do so, they right thing to do by both bookies, casinos and regulators is to make things as difficult as possible for those kids to gamble away the money of their parents and possibly getting addicted to gambling at a very young age.
This is not the key argument in a topic like this. Even if they were unable to bypass restrictions it would have a big effect an effect on them because of the repeated exposure. I have talked about this in this thread, most of the effectiveness of advertising does not come from someone having access to the product or not. It is about creating associations in their brain and making them as deep as possible, it is like a big propaganda machine. This is the reason why many tourists go to famous fast food chains when they visit other countries when there is far better food and cheaper everywhere around them, because they have been exposed so many times to this and eventually they started to eat it and create a deep habit. So even if kids are not able to access the websites if they had strict KYC, they would join the gamblers when they grow up to become adults. This is why they need to be protected strongly, and not with some cheap measures like the one here. We can say that this measure is something, but we can not say that it has a significant effect on the children.