It's sad that too many people don't understand how life works outside of their cubicle.
If you are self-employed, you’re a business and you have to behave as a business. I, for example, am a business so I understand exactly what you are talking about. At one time in my life, though, I lived in a country where withholding for salaried employees was the responsibility of the employer. There were no deductions. No April 15 filing. Nothing. It wasn’t your responsibility. There was no way for you to make a mistake and it wasn’t your problem if a mistake was made. So I know that kind of system can be available for salaried people. For people who are in business for themselves, with materials to buy and costs to detail, then you are right, there is no escaping a more detailed accounting.