There are hundreds of wallets, some of them OSS, some of them closed source, some of them homebrew. I have used several different wallets, including some that I have coded myself from lower level cryptographic APIs. This is the beauty of it: users are not limited to MetaMask, just like users are not limited to browsing the web in Chrome - despite it obviously having major market share.
Where do you live? Almost all of Africa, many parts of South-East Asia, India, many parts (if not all) of China, and nearly all of South America are heavily cash-based societies. Try to work your way up to Northern Burkina Faso, which has little to no electricity in most places, and your stance on cash being a poor substitute will quickly change.
You don't have to use a regular bank either you know, cash is way less traceable than Bitcoin.