It's not in their interest to lie in the long term. Those companies who lie are scams and they're spotted pretty quickly (e.g. Theranos, Nikola). Elon has made some mishaps, such as 'funding secured @420' tweet, which he was punished for. Public companies have to be pretty careful in their communications. Making promises with too optimistic schedules is not lying, it's just an error in forecasting, and is common in technology.