I feel like most parents dont even understand how bad it is. Even sites that technically don't allow "phonography" have plenty of gratuitous nudity (and yes, nudity is in the same class of problem) if you know where to look. Frankly you can actually find pornography there too if you dig deep enough. CSAM and lewd images of children as well
Thats the real issue, and while I don't necessarily want pornography banned, or require some government ID, I really hate this whole "oh well guise, can't ban it and giving ID access is dangerous, our hands are just tied," mentality that seems to be so pervasive. Like if your kid wants to find explicit material, and is determined to do so (as all teenagers are), then short of constant surveillance, they will find it. There has to be a middle ground between "mandatory ID to access things" and "oh well can't do anything."