Quite a few years ago, the US passed COPPA, which imposes quite strict regulations on sites that collect information from children under 13. The end result was that many sites banned users under 13 years old. This isn't really that big of a problem; it could be argued that there are few sites not specifically designed for children that children this age have any reason to use.
When the European Union passed the GDPR, they included a provision that children cannot consent to data collection, and allowed member states to set the age of consent anywhere from 13 to 16. At least some picked 16. Why? Did they not expect the same thing that happened to children under 13 in the US with COPPA to happen to children and teens under 16 in the EU? The argument that most sites not specifically targeting children are not relevant to them is much weaker when "children" are defined as anyone under 16 rather than 13.
Did they somehow not expect this to happen, or did they determine that protecting the privacy of teens 13 to 15 is more important than their ability to use the Internet with few limitations?