Depends on the situation and the characters. If they're playing against someone they know isn't quite as skilled, they might feel confident enough that they don't need to get DA DAMAGE right then and there. Instead, they can be fairly confident they'll be able to land the next hit to kill your character without having to spend resources.
On the other hand, maybe you have characters that they don't feel confident facing with their anchor unless they have meter/drive. It could also be that the character they're using doesn't have particularly good combo options from certain screen positions, so it's not worth spending the meter or drive. Instead, they'd push you to the corner where their resources could be better spent.
They themselves might still be figuring things out, and don't even know any decent combos for their 1st or 2nd character. In that case, saving meter for their last character that they're confident in their combos with would be a pretty smart decision.
Me? I've got no problems spending meter, so long as I have a decent reason to.