It takes a few hours and $5 to send $100. Paypal anyone? https://www.reddit.com/r/Bitcoin/comments/6val1d/a_5_fee_to_send_100_is_absolutely_ridiculous/
The mining fee depends on how many bytes are used in the block which in turn depends on the number of inputs there were to the transaction. It also depends on how soon you want the transaction to clear. The fee does *not* depend on how many BTC were transferred. Modern wallet clients lets you control how much fee you pay. Many users are overpaying fees out of fears of having a "stuck" transaction. But if you're willing to wait a few hours instead of minutes you can significantly reduce the fee. Wallet clients also let you pick and choose which addresses to feed to the transaction. Sometimes manually choosing inputs can reduce the fee depending on the client.
Cryptocurrencies are useful for payments that are very large, very small, very fast, very international, or very automated (so not so much for average amounts like buying a cup-of-coffee). Although (we have to admit) currently the "very small" doesn't work anymore (just too popular). But that will be solved in the near future when new innovations like the Lightning-network will be rolled out.
I call myself technically savvy, but I don't have patience and stamina to read through the explanations, specially when at the end the word is a big maybe. But here is another POV: https://cryptoinsider.com/quickly-will-bitcoins-lightning-network-able-lower-fees/ My take is that nobody really knows how it is going to work or how much the fees going to cost. Dandy....