Because 250,000 watts of electricity plus liquid is a great thing to be handling every day.
That's well over the equivalent of 4000 old fashioned incandescent 60 watt light bulbs burning at once. Imagine the heat waste (plus the energy needed to just cool the cables and transformers). Then imagine the power needed to charge dozens of cars at once. If one believes that Tesla is the future, one should invest in coal and natural gas.
When the charging stations explode, it will be spectacular. Sort of like when a big power transformer blows.