Honestly, and I apologize because I know this sounds a bit dismissive of your issue, but this is player confusion, right? Players shouldn't have to worry about any stat block of a monster, or concern themselves about how a monsters attack modifiers are done. That's the realm of the DM.
And even if players do insist on looking at stat blocks, of all the ambiguities with rpg rules, that seems a pretty minor one to get caught up in. Like most every other thing that is ambiguous, just make a ruling and carry on.
Well, it came up for two instances.
1) our party was getting horses and noticed the mistakes in the stat blocks in the MM and I looked up the errata, and
2) we were fighting dire wolves and the ranger's beast companion wolf was fighting one.
Between the players and DM, these blocks were looked up and the DM (who is normally a player) noticed the differences between the wolf types--why one seemed to be using DEX and the other STR.
Basically, we realized the wolf's bite is a "finesse" weapon attack and the dire wolf is not (using STR), but nothing in the MM has any section really about natural weapon attacks, and how some use DEX and others STR.
The player who has a monk (in our other game) commented about how it must be like how he can use DEX or STR, and another commented about how normally unarmed strikes, the humanoid equivalent of natural weapons, has to use STR. Another who has a dragonborn sorcerer (other game) with the racial feat dragon hide (for the AC) asked why he can't use his DEX for his claw attacks, since it states it adds his STR mod (which is 0) and he never uses it or even considers it.
And so a lengthy discussion ensued about the problems with having inconsistency, lack of information, and so on.