I don't think I need to tell anyone that running any pump dry, unless it's sold to do so, is a bad idea. Why didn't they pump the water from the tank to the pl

I don't think I need to tell anyone that running any pump dry, unless it's sold to do so, is a bad idea. Why didn't they pump the water from the tank to the plants? Why did they rely on pressure? That puts a whole lot of strain on the pump.