I'm not sure if I can fully answer your question, mainly because I am just a consumer and not involved in any way in the industries. But I do (slightly) recall on eBookJapan (before Yahoo.co.jp bought them out) older manga was (or looked/felt like) scanned, but later on, they would remaster, and sometimes even digitally publish black-and-white version and colored remastered version, and charge differently.
Also, I am not in a market as a consumer of translated tankoubon (i.e. as you say, "Asia region" and western licensors) other than Japanese so I can only answer for digital manga I purchase from the few places I can purchase from direct in Japan (before eBookJapan was owned by Yahoo.co.jp, I was able to pay with non-Japanese credit card, now it is more difficult to buy - mainly I presume due to copyright law only protects Japanese publishers in Japan) but the scanned ones I've seen were only from my curiosities of nostalgias of "oh I want to read this manga again" and did the tachiyomi to see if I really wanted to purchase it, so I have no purchased copies of any tankoubon that looks like it was scanned for a proof.
Again, I do not know if I did answer at least a little, of your question, mainly because I am not in the market for other Asian translations, but as mentioned, due to copyright limitations, if it is scanned, I have second thoughts that they might not be a legitimate publisher, but you can probably go to eBookJapan to see if they have (as in, they are selling) a digital version of the tankoubon you are interested in, and if they sell it, most likely there exists a legitimate digital version from the publisher (I am not here to preach about piracy or how important it is to support manga authors, so leave it up to your discretions on whether you want to pay/support scanned market), and I hope I was able to indirectly answer some parts.