From things I've read and put together:
Europe is using 3.4 to 3.8 GHz
US is using 3.7 to 3.98 GHz
The radio altimeters use 4.2 to 4.4 GHz
So the spacing in Europe is 400 MHz, which is fine, but in the US it's 220 MHz
The other thing is, apparently, the US radio/antenna setups are up to 2 times as powerful as those used in Europe and the antenna are installed in vertical positions in the US vs they're tilted away from any finals/flight paths in Europe.
So it's not an apples-to-apples comparison when someone says "well Europe did it, so it's all fine!"
On top of that, the AT&T spokesperson quote of "We are frustrated by the FAA's inability to do what nearly 40 countries have done, which is to safely deploy 5G technology without disrupting aviation services, and we urge it do so in a timely manner" (Megan Ketterer, an AT&T spokesperson)
What? The FAA isn't deploying 5G, the wireless carriers are with the backing of the FCC. If anything, you should be asking why your own companies (and by extension the FCC) cant' deploy 5G without interrupting aviation services. I've seen reports where the concerns from the FAA were forwarded to the FCC for quite a while now, but...