What were these parents thinking? This isn't a new issue. People have been reading stories like this in the news for a decade and still they hand their kid their iPad and say "go play over there while dad watches the news..."
You can literally use your phone and google/apple account as a credit card nowadays. It's irresponsible to just hand that to a child. Ignorance is not an excuse. (that said, of course there should be consumer protections in place to limit the damage)
I disagree that it's as simple as just blaming the parents. As a technical community it is easy for us to assert that there are probably optional restrictions somewhere but many parents who are not technically-minded will not necessarily make that connection. Manufacturers/vendors of these devices simply don't do a good job of advertising to parents about these risks and the options available to restrict them.
iOS, as an example, does have the ability to disable in-app purchases using the "Content & Privacy Restrictions" settings, but unless you dig through the device settings and found them (under "Screen Time" no less) then you would not know that those options exist. Given the obscure naming reducing the chance of them ever being found, they had might as well not exist.
Apple could do things to improve this. They could clearly ask about parental controls up-front during the device initial setup, they could clearly place them at the top-level of the Settings app and label them "Parental Controls", they could even include a bit of paper in the box or some printed text on the packaging that explains where to find those options.
I'd argue it's the parents responsibility to educate themselves in this regard. Again, this isn't new news. If you can make a purchase on the device, your child can make that purchase too. Certainly, the OS can flag more warnings during the setup of the device etc. but I doubt the people getting into this situation will pay any more attention than they've evidently done so far (which is to say very little)
You can literally use your phone and google/apple account as a credit card nowadays. It's irresponsible to just hand that to a child. Ignorance is not an excuse. (that said, of course there should be consumer protections in place to limit the damage)