For many Americans it’s actually pretty simple as long as they’re working with a standard W-2 (form you get from your employer with the year’s wages and taxes and stuff filled out). Many tax prep services will even import these numbers automatically and all you have to do is click through the questions and optional things like if you want to donate your returns to anything or pay estimated taxes for the next year - mostly stuff that most people aren’t concerned with anyway.
Taxes here start getting complicated when you are an independent contractor (you’re responsible for holding out taxes from your income since you don’t have an employer to do it for you) and/or have non-standard sources of income like stocks, shares, real estate holdings, etc. which the IRS may or may not have information on, thus why you need to provide the info.
Most of what has made calculating taxes and paying/getting returns a pain in the ass is tax prep companies like TurboTax lobbying to make and keep the tax filing process a confusing one, with the goal of steering you into paying for the non-free filing options.