I guess that the EU could force Apple to substitute USB-C to USB-C charging cables for the USB-C to MagSafe 3 ones. An increase in standalone sales of USB-C to MagSafe 3 charging cables would probably soon follow.
USB-C to MagSafe 3 is not required. You can simply plug in directly to one of the USB-C ports if you'd rather not use a Magsafe 3 connector. The Magsafe 3 option, though, gives you a faster charging.
With respect to faster charging …
The version of USB Power Delivery that the MBPs implement, and that the EU directive seems to reference, allows for a maximum of 100 watts of charging power. The 14" MBPs can "fast charge" with 100 watts, but the 16" MBPs need more than 100 watts to "fast charge". Using Apple's 140 watt brick, and MagSafe 3, lets them get it.
To be clear: The 16" MBPs will charge over USB-C … but only at regular speed.
There's a
new version of the USB Power Delivery specification that allows for delivering up to 240 watts. It involves negotiating the use of new, higher voltages. It would be logical for future revisions of the 16" MBP to take advantage of this new Power Delivery specification.