My observation, being born and having lived in Brazil for my whole life, is that there's a power/authority/seniority dynamic involved, too: If you have a meeting with a customer, you should be on time, but it's okay for them to be late. When meeting with your boss, they'll probably be late, but you probably shouldn't be. Internal meetings within the company usually start later than meetings with other companies. Once you know people professionally for a longer time, you'll also be more comfortable arriving later.
There's definitely a dominance element here in Mexico, too.
My Mexican friend traveled a lot here for work to meet with various executives. These executives would be the ones who set the time.
She'd drive four hours and arrive at their office for a 8am 1-on-1 meeting and be directed to a sofa outside their room. She told me often 30+ minutes would pass and the guy would be in there twiddling on his smartphone, she could see him right through the blinds.
It was like some proof of time-burn to remind you that they had the power.
My observation, being born and having lived in Brazil for my whole life, is that there's a power/authority/seniority dynamic involved, too: If you have a meeting with a customer, you should be on time, but it's okay for them to be late. When meeting with your boss, they'll probably be late, but you probably shouldn't be. Internal meetings within the company usually start later than meetings with other companies. Once you know people professionally for a longer time, you'll also be more comfortable arriving later.