Because I can’t quite see the difference

Parents can (and MUST) monitor what happens in their home. It was expected for the past thousand years, and now it's the duty of everyone to take care of anyone's children for some reason. To get to a porn store, you need money to take the bus or you need a car, then the owner of the store can kick your ass or call the cops if you're underage. Remember that less than 50 years ago, the local priest could smash your face if you didn't behave properly in the street, With the internet, parents are the sole responsible for what their kids do, but they don't want to take any responsibility for it. The solution would be a mandatory parental control on every computer, but parents wouldn't like that.

government overreach to have the same expectation of online pornography providers

Because that overreach happens to remove all my privacy thanks to a few idiot parents who don't want to do their parenting jobs in another country, and I consider that unacceptable. We can do some whataboutism and say that since parents in Afghanistan don't want to watch porn, all the porn of the internet has to disappear. Same for blasphemy and freedom of women to browse the internet.