It's more likely still that the person answering emails didn't know the answer, and either was unmotivated or unable to put the question in front of someone who

It's more likely still that the person answering emails didn't know the answer, and either was unmotivated or unable to put the question in front of someone who did know the answer and then follow up with them to respond. This is when having contacts inside a company helps. Either be a big enough customer to warrant their attention by default, or make friends with the company rep when she calls or stops by. If you aren't a large enough customer to have either of those options available to you, then you get the attention they feel you are worth as an end user.