...because practically every site says..."Teen". Now it looks like you are into teenage girls as opposed to young women.
"Teen" refers to petite or college age 18-25 year old looking women regardless of actual adult age. This is the most popular selection of males in surveys of any age, it's likely because mating with them offers the most chances of success of offspring. Their bodies are healthy, active and capable of having lots of children. (on the other hand younger women prefer slightly older guys and older women prefer slightly younger guys)
"Pre-teen" represents below legal consent of age 13-17 years old girls.
Of course every country the age of consent is slightly different. It's up to the website to ensure that their content is legal going to the respective IP address of the country. If they don't, then they are usually quickly reported and could be IP banned if they don't correct the issue.
Of course most well seasoned law enforcement agencies know this, but I agree the general police are usually not hired for their brains or knowledge, but their aggressiveness. To them suspects are dogs to be brought to the pound and let others decide their fate. If your feeling guilty of watching legal "teen" porn you shouldn't be, most all websites are in compliance with local laws as they are trying to build hit traffic/advertising revenue.
If your surfing the DarkNet, 4chan, Masterchan, 8chan or non-nude modeling sites your certainly looking for trouble as people post/link to cp there and the mods are either intentionally slow or don't check the content or links before publishing. If your downloading via P2P, your certainly risking as people spike good content with cp.
All in all the clearweb is pretty clean, it's because people report cp sites quickly.
In the old days of hard drives, it was possible to clear one's caches, web history etc. and then use a 7x scrub of free space to clear the hardware (takes many hours on large drives or it can still be read by magnetic devices). However today with SSD's they cannot be securely erased and the NSA recommends they be disintegrated which gets rather expensive and tiresome reinstalling the OS each time.
My opinion is to use a open tower specifically for porn surfing that you can quickly dispose or reformat the HD in case of ambush by a rotten link, keeping a system image on a external drive that you can re-image back on. You see the problem is when the cops review one's system, they include the deleted images as evidence as well, just the accusation of being a cp lover is enough to ruin one's life and cost a fortune to move elsewhere even if proven not guilty. If guilty, it's better to find another country to live in rather than try to exist in the one accused of.