Yes, OSM is inconsistent. There's a simple reason for this: Mapping is dead simple in theory, but looking further into the nitty gritty details reveals a whole lot of interesting problems.
And if Brazil, as a culture, solves the real-world problems with traffic, naming things, writing maps, etc., in some way that's almost, but not quite, entirely unlike the way the UK or Japan or does, that's just life. Deal with it.
The other side of the problem is that the OSM creators themselves were somewhat naïve when they started the project (and some contributors still are ). So yes, the whole set of tags is somewhat inconsistent at times.
But then, the very idea to go and map the entire world is so damn daunting that anybody who does not have that bit of naïvety wouldn't even be able to get started. They'd throw up their hands when confronted with the sheer magnitude of the problem, and leave mapping in the hands of some data-hoarding corporations who are at least two years behind the Real World.
That kind of contribution economy just plain works. It works for Wikipedia, and it does for OSM. This, more than anything else, IMHO is the whole point of having this huge thing called "The Internet".