You's have to give more particulars!
It's got nowt to do with EU (or US).
More volts is always better as losses are less.
I2R!
There are lots of 50V LDMOS devices now from NXP and with GaN and SiC going upto 900V much higher voltages can be used and efficiencies increased.
Folk use 12V because theyre lazy and lots of folk have some CB PSU they think will be fine!
That and it's in your car/truck etc...
48V is a 'telecomm' standard as all base stations use -48V.
48V SMPSU's are dirt cheap and the 10A version ideal for 100W (400W pep Class E Tx).
Str.