There's no reason everyone shouldn't know things like quantum mechanics, relativity or molecular genetics. All people have to do is pick up a book and read.
Same goes with languages, just practice. Anyone can learn a language in a year if they put effort into it.
a scientist is a professional.
Anyone is free to learn and/or understand whatever science they want, but without a career in scientific research, you can't be a scientist. There are definitely non-scientists that are more knowledgeable about science than some scientists, but they're not scientists because that's not their career.
The point is anyone can or should be able to become an equal authority on something. A piece of paper like a degree is someone that gets you a job.