But the trust level groups are subsets of each other - all users in TL1 are in TL0, all users in TL2 are in TL1 and TL0 etcetera.
So it doesn’t grant the permission to the group, but it does grant it to the group members.
IMO that would be a worse user experience than having a dropdown.
Not just because of the scrolling and complete loss of overview that would occur with large sets of groups, but because your last screenshot would only need the line “everyone - see”. The rest is redundant.
You want to add a lot of friction for every time someone looks at the settings, while removing friction for the few times that someone modifies them.