My Japanese teacher said learning when to use “wa” or “ga” in Japanese for us is like him learning when to use “the” or “a” in English.

The rules for wa/ga are much simpler and easier to internalize.

So is for most Slavic people. Only Bulgarian has definite articles.

And, on the general theme, the Bulgarian rules for using definite articles are closer to the French rather than to the English rules (I'm fluent in French and English, learning Bulgarian ;)).

I'm not going to try for a Bulgarian example of the difference, but here's an English vs French one

"A Paris, les oranges ont l'air ..."

"In Paris, oranges appear ..."

One could possibly add a definite article to the English sentence, but one definitely cannot remove it from the French one.

I'm not a linguist, but I believe there is a direct relation between the French article and the Bulgarian one - Bulgarian articles are characteristic of the Balkan sprachbund[0], likely influenced by medieval Romanian, a romance language.

[0] https://en.wikipedia.org/wiki/Balkan_sprachbund