I'll readily admit I haven't used them as much as nahuel ( hi tiger!) and really only for international flights. We've probably used them on 5-6 occasions over the past few years add another couple of trips by immediate family members. My sister -in law used them as late as September, she was late. On every occasion we have used them, they have been late. No, hang on my mother used them about three years ago and I think they were on time on the outward journey. We have Argentino friends who live now in Australia. They used them earlier this year.... late again. In fact they've sworn that they'll only be using the Qantas Sydney- BsAs service in future despite the higher cost. Brazilian friends all report the same. As, like them, the bulk of our flights with Aerolineas have been trans- pacific, Brazilian air traffic control issues have had no bearing on the delay.
I'm only relating personal experience. Maybe we have been terribly unlucky. Maybe the rude, arrogant and thoroughly disorganised staff I've had contact with are just a tiny minority of an otherwise wonderfully efficient and customer focused organisation. I wish that were the case. I have no ideological issues with Aerolineas being nationialised and due to limited range of carrier options on the routes we most regularly take I have a vested interest in it being a good and reliable service. Alas to date that has not been my experience and we only fly with Aerolineas on the basis of cost availability. I really hope they do improve.
BTW LAN aren't much of an improvement. You trade (relative) efficiency for dishonesty and in my wife's experience the prospect of outright racism.