Re: No they don't
Many if not most switch mode power supplies SMPS convert the incoming 50Hz AC to DC then drive a small/tiny transformer with 10kHz to 1MHz AC signal.
Most PCs and laptops and 5V USB chargers could probably take AC or DC,
It should be noted the peak voltage of the 240V mains is 41% higher (339V) than the RMS.
I heard France had a DC grid, in the old days you had a DC motor drive an AC alternator.