30% is huge for an aircraft. Not only do you need more fuel for each trip, you need extra fuel to handle carrying around the extra fuel. (not necessarily intuitive starting out but aircraft deal with amplification factors, energy added ounce of fuel will require a greater than unity number of additional ounces of fuel for equivalent performance)

Comparison to electric flight is a bad comparison as until very recently electric flight was basically considered to be impossible with present technology.

Electric flight in the history of flight has never been “impossible.” Anyone who told you it was impossible didn’t have the capacity/desire to think in terms of fundamentals beyond existing rules of thumb. (“Existing technology” is a nice weasel term, but we’ve had electric flight of various types demonstrated decades ago.)

30% is not high. It might convince you to do some drag reduction on your aircraft to compensate. Most small general aviation aircraft are terribly aerodynamically inefficient even compared to state of the art aircraft 50 years ago. 30% is barely relevant for the short intracity trips in this article.