They don’t need to be cheaper, just the same price or even slightly more given the running costs and maintenance are far far lower (no filter changes, no oil changes, no timing or fan belts, etc etc). People will spend more upfront because over the life of the car they spend far less. That why prius became so popular - they were $10k more than the same ICE car but you saved $20k in gas over the 5-10 years you owned it.