T oday's bicycle manufacturers offer a proliferation of systems for shifting gears. Shifting has been made easier by the introduction of twist grip controls. There is renewed interest in internally geared hubs. Some of us may remember the English 3-speed systems. Different from derailleur systems, the rider needs to stop pedaling briefly while changing gears.
Internal gears are relatively expensive.
It is hard to make such a case for most riding, even in hilly areas. Electric bikes typically provide 200-400 Watts of continuous power. Only a world-class bike racer is capable of pedaling 400 Watt for half an hour. Clearly with such dramatic power added, with relatively little extra weight, the need for multiple gears is less while riding an electric than a pedal-only bike. Between the marvelous new technology and the many systems available shifting has thus become easier, more reliable, and more enjoyable.