Do a bit more reading. Chat GPT is a tool, a person is a person who can make their own decisions. When you cheat with ChatGPT you are responsible. When you cheat by paying someone to take an exam on your behalf then you are both responsible. When this is done for financial gain by one party it becomes criminal fraud.
The person jailed pleaded guilty to the following criminal offenses:
1. Fraud by false representation - by claiming to be someone you are not you're in breach of the Fraud Act 2006. ChatGPT doesn't do this, the cheater does this.
2. Cause computer to perform function to secure unauthorised access to a program/data - using someone else's credentials to access a computer system is a breach of the Computer Misuse Act 1990. ChatGPT doesn't do this, it only provides information, the cheater uses the computer.
3. Conceal/disguise/convert/transfer/remove criminal property - This one may be weird to some, but the name of the act should clarify: It's the Proceeds of Crime Act 2002, you're liable here when you commit crime for profit.
Englishing has nothing to do with it. The University has nothing to do with it. What you think words mean is irrelevant. There are laws, laws have definitions, those definitions and laws applied to this case and the man was jailed by someone trained and competent to interpret those laws.