In the beginning days of e-bikes, the choices were to build your own. Many were rigged around a modern bike using batteries, motors and electronics from tools, household items and so on. The retail options for turn-key electric bikes were very limited and many with poor range, power, and low craftsmanship.
As the industry grew so did the retail options. While turn key ebikes have greatly improved over the years so have their e-bike kit counterparts. Today you can purchase any electric bicycle type including cruisers, cargo, mountain, commuter, road, trikes, folding and so on. In general, many of the higher-end factory ebikes have reliable electronics, dependable lithium batteries and motors.