That’s not the extent of software freedom. You can personally modify someone else’s free software if you want. But if you are providing the modified software to others, either as a free or a paid product, then you have to provide the users with a copy of the modified source code. Modifying GPL licensed code and using it commercially without supplying the modified source code is the primary source of free software license violations.
Free software is defined as software that allows the end-user to use, distribute, and edit it in any way they choose.
Can you give an example of a scenario when police would enforce a violation of that?
That’s not the extent of software freedom. You can personally modify someone else’s free software if you want. But if you are providing the modified software to others, either as a free or a paid product, then you have to provide the users with a copy of the modified source code. Modifying GPL licensed code and using it commercially without supplying the modified source code is the primary source of free software license violations.