Technically speaking you are right: there is almost no police, no public health care (quality is too low to even step foot in a public hospital), school are pretty low quality, and people tend to be rude. But for a temporary gig (I am in Romania due to taxes for a few years) it can be beneficial. It's not as bad as say India or Pakistan as east eu countries are orders of magnitude more developed, and if you can put up with the nuisance for a while then you can return to your western country and maybe afford a deposit to stop living with flatmates as an adult. Worth while in my case.
I don't remember exactly the numbers for self employed, but if his are correct (and they seem a bit off, maybe because of the missing health insurance), the difference is basically 5-600 BGN, so 5-6pp.
*) Arguably because (while they could easily afford to pay more tax) higher income employees usually get taxed on their actual amount of income as opposed by the rampant tax evasion among employees with lower pay and their employers (so called grey economy: employers declare they pay a given employee the BG equivalent of the US 'minimum wage' which the employee receives monthly via bank transfer, while the rest of the salary is given in cash and not declared).
While I definitely agree with that (and in fact my own reasons to move to Bulgaria back in the day were not about taxes at all), could you elaborate on the not-entirely-correct part? What exactly is not correct?
Also there are other small things to consider:
* Healthcare in Bulgaria is severely underfunded and understaffed. Not only that, but the incentive system for hospitals is currently IMO completely broken, as they get paid per patient i.e. more sick people = more pay, not more healthy people. My current belief is that you need to live in a large city if you want to have a chance to survive an incident or a heart attack/stroke. Source: trust me, I live here, have lost several family members due to poor healthcare, and have had one receiving incompetent treatment so the hospital can receive more money from health insurance.
* Same goes for childcare/education.
* * There is currently a severe deficit of kindergartens in the large cities -- Sofia (~10k children left out), Plovdiv, Varna and Burgas.
* * Bulgarian public education has been in a freefall for the last 10 years as evidenced by dropping results in state exams and international studies (https://gpseducation.oecd.org/CountryProfile?primaryCountry=...). Private schooling is available in large cities and unsurprisingly is limited. Take into account potential need of home-schooling if you plan to start a family here.
* The public institutions are (currently) not working or corrupt. There are issues with the judicial system, the prosecution, the police, etc. Tl; dr: better hope you won't have to deal with those before major reforms and definitely don't rely on having your rights protected by them. You are on your own here.
Do not be under the illusion that Bulgaria is just like $western_european_country but with less taxes and cheaper housing. Everything comes at a price. You will not find many things you take for granted in your home country here.