666dollarfootlong

Why is it that we use voltages and watts more often than amperages? 9v batteries, 12v car battery, 1000W Microwave oven. But amperages not so much, even though its "half" of what makes power, A*V=W. What property of amperes makes it so "unnecessary" to be aware of?

Bonus: how many amps and volts does a typical 1000W microwave use?

I feel like it would be useful to know exactly how much alcohol is in a can or a bottle. Also why is alcohol the only thing measured in percentages and not sugar or caffeine or medicine?