British outlets are fused for _lower_ current than american outlets, not more: 13 amps instead of the 15 or 20 that's common here. It's the voltage that's higher, which means that the power transferred for a given current is about double.

Fused for 13A running off 32A ring main.

Continental Europe uses 16A radial circuits so the current rating is higher there.

EDIT: Of course, you can't run two kettles on one radial, but you can on one ring.