I see your point but I am not sure about this. I suspect a lot of people use just as much water but spread it out longer. In California there are a lot of devices mandated to reduce consumer use (flow restrictors and so on), but interior water use often demands fixed quantities. For example if you want to have a bath rather than a shower then people will use the capacity of the tub, likewise if you boil water for cooking a flow restrictor just means it takes longer to fill the pot to the required level. So people use just as much but just suffer lower pressure.

Toilet cisterns arguably do reduce usage but then many people complain about less effective flushing which requires additional water; I don't have data to know if these objections are just a cliche or reflect an actual problem. My understanding is that lawn-watering is the biggest waste of water by consumers, to the point that some local authorities will subsidize people reorganizing their gardens to be more suitable for a dry climate.