As has already been stated, many foreign-owned, multi-nationals operate out of Mexico and the business structures of these organisations will probably be heavily influenced by the corporate culture of the parent company.
Therefore, it may be possible to interact with an operation which works in a flat, matrix-style.
However, indigenous Mexican culture tends very much towards the hierarchical in both personal interactivity and the way in which business is structured. It is best to expect that the organisation you are dealing with will have a very centralised decision-making approach with all decisions of any importance being made by a few key individuals at the top of the company.
Take the time to understand the structure of the business to ensure that you are dealing with the right people. Time can be wasted negotiating with people who have little or no authority.
Ensure that you do not insult Mexican senior management by sending your junior employees to deal with them. It is always best to match levels of seniority during any interactions. (If a Mexican contact sends their junior people to deal with you, it is probably a good sign of lack of genuine interest on their part.)