This is not my experience. My costs are higher, but the costs offset and then some by tax advantages.
Sharing here, to give a picture of what a real single person LLC looks like, compared to a vanity hobby LLC as described by OP.
I'm a contractor with a registered LLC S-Corp in the US. Almost all of my income is 1099 from one source. I was converted from W-2 to contract when my employer was acquired, my job role did not change. You might call me a misclassified full time employee. I could report this of course, and then I would burn my professional contacts and lose my job. So I don't.
I hire myself, pay myself a fair market rate as a salary, and run a payroll just for me. And I provide myself a few benefits from the LLC, like health insurance.
I'm required to keep up with a pile of quarterly and yearly fillings between the state, county, city and IRS. This is a non trivial amount of time and effort. I have to maintain separate business books and bank accounts in coordination with my accountant. I don't actually get to access the money I earned until it exits the business entity through a controlled process. I have to file business taxes separate from personal taxes. I still have to pay quarterly estimates on my personal taxes too.
My family health insurance is roughly $12k this year. If I purchase that insurance directly, I use post-tax income to do so. I'd pay ~$4k in taxes to take home the ~$12k income used to buy health insurance. But when the LLC buys the health insurance and provides it as a employee benefit, the ~$12k is not taxed.
The salary I pay myself is taxed at ~37%. The same as if I just filed as self employed. But the business income I earn over that salary is taxed at ~20%. This is the biggest advantage. The gap between a "fair market value" for my role, and my actual contract rate. In that gap, the LLC structure saves me 20% on taxes by labeling that portion of income as "shareholder profit disbursement".
Rough yearly costs:
$150 registered agent service $150 state registration filing $2500 tax prep and account services throughout year $1500 payroll services, including payroll tax filings
Rough yearly tax advantage:
$15,000