This is my understanding as well: mirar [la] tele is common in Mx & Central America. Based on looking around the internet and this conversation here, it appears that ver is used for watching tv esp. in Spain but that it is not uncommon elsewhere and that the two are synonymous in many Spanish speaking places outside of Spain. It appears that omitting the definite article is not uncommon. Here's a link to a site (seemingly located in the US) that uses mirar a lot: https://tecnovortex.com/2013-el-ano-que-deje-de-mirar-television/
Basically, ver talks about the visual information you receive ("to see, to watch"), while mirar is talking about what your eyes are doing ("to look at").
In the case of watching TV/films/sports/etc., most Spanish dialects use ver, but mirar is also good in some places. Mostly, though, "mirar la tele" would be taken as "looking at the TV", not actually paying attention.
Dunny, that translation is also possible, but it's usually not what this kind of sentence is used for. In fact, when you want to say "Why are we not doing something?", I'd go for the Progressive form in Spanish:
- ¿Por qué no estamos viendo la tele? - Why are we not watching TV at the moment?