Two things can be true. Yes this appears to be negligence on the part of OpenAI.
However, making a secure 'sandbox' is quite hard. There's a huge variety of exploits that exist today, including many we don't know about. Strong models have already shown a capability of finding and using such bugs.
Even one of the strongest boxes we can imagine, literally just a text interface a human can read, has been repeatedly shown to allow unfriendly AI to escape containment: https://www.lesswrong.com/w/ai-boxing-containment
However, making a secure 'sandbox' is quite hard. There's a huge variety of exploits that exist today, including many we don't know about. Strong models have already shown a capability of finding and using such bugs.
Even one of the strongest boxes we can imagine, literally just a text interface a human can read, has been repeatedly shown to allow unfriendly AI to escape containment: https://www.lesswrong.com/w/ai-boxing-containment