I was pretty impressed with the low tech solution in the article. I thought of the same thing as you at first, digital menus online, or on the table, or.. digital paper menus.

They instead just offer a discount up front. 10-30% if you book a particlular time. So most everyone except the fractional multiplier afraid will know how to adjust the prices on the fly.

as an aside - many cheap places that I end up at have menus posted outside for the foot trafic, that may be the perfect place to replace it with a digital sign for dynamic pricing.