$20 is a little high. ETH transactions are variable cost; more complex transactions cost more. In order to get the price of a simple transfer you can take the current gas price (for example, from https://ethgasstation.info/index.php), which is 87 right now, multiply that by 21000 (cost in gas of a transfer) and divide that by 1 billion. So a transfer costs 0.001827 ETH or ~$6 if you want to happen within a few minutes.

So yes, it's currently not practical for microtransactions.