Currently the default trust list in your browser is solely decided by your browser. More specifically there's an organization called the CA/Browser Forum where all the browser vendors are. If you want to become a CA today, you go to the Forum, submit your proposal, and then the browser vendors decide whether or not you're trustworthy. If a CA misissues certificates or otherwise screws up security, that evidence goes to the Forum and then browsers decide how to deal with that CA. Notably, in the worst case scenario, the browser developers can and
have decided to completely distrust an entire CA, completely destroying their business. This has happened multiple times.
eIDAS changes this by, effectively, creating a special EU government analogue to the CA/Browser Forum. All browser developers in the EU have to trust eIDAS's CAs. This is a transfer of power from a voluntary industry consortium to appointed EU technocrats.
All those existing government CAs are currently audited by CA/B. If Greece gets caught misissuing certificates they can have their CA roots revoked by the browser vendors. The concern is that under eIDAS, the EU could just not revoke the certificate, and the browser vendors' hands would be tied. They'd be forced to accept known bad CAs and every cert they sign, including the spyware ones.
eIDAS changes this by, effectively, creating a special EU government analogue to the CA/Browser Forum. All browser developers in the EU have to trust eIDAS's CAs. This is a transfer of power from a voluntary industry consortium to appointed EU technocrats.
All those existing government CAs are currently audited by CA/B. If Greece gets caught misissuing certificates they can have their CA roots revoked by the browser vendors. The concern is that under eIDAS, the EU could just not revoke the certificate, and the browser vendors' hands would be tied. They'd be forced to accept known bad CAs and every cert they sign, including the spyware ones.