So the way I see it there are two things going on:

1) The sadness that you do not take up nearly the kind of space in your T's life that s/he takes in yours. This isn't the same as T not caring but for many of us there is no getting around the fact that this inequality feels like a bit of a loss or endless yearning. Maybe this is experienced differently by people who got enough from their parents. When you add the fact that you pay them it seems like "geez, I'm not important to them they way they are to me AND I have to pay! They must not care about me at all!"

2) This notion that the financial transaction somehow cheapens the sincerity of a T's care for her/clients (this is kind of the same way we talk about sex work). This is a bit unfair really. Do you think nurses and teachers and caregivers have no feelings for the people they look after? Do you care about your own work beyond your paycheck? (This will depend on how much your job means to you of course... But I bet many of us do). Sure our primary model for emotional work (parenting) is an unpaid job but this hasn't always been so and isn't true everywhere. Do you think in agrarian societies (where wealth depends largely on having children to do work) parents love their kids less than in urban societies where kids are a financial drain?

There is almost always a financial relationship between people who care very deeply about each other (think about marriage for another example.) Often it's a complex affair where one person does a lot of unrecognized emotional work in order to have some financial security. Think about the kind of marriage where the wife provides sex, childcare, a listening ear etc and the husband earns a paycheck. It can be messy and fraught with resentment. Whereas with your therapist it's all there on the table from day 1: The whole endeavour is about the client's feelings and all you need to do is plunk down a check. Your T will never (or should never!) sulk about the dishes or be hurt that you forgot his birthday or make you feel bad for not wanting to have sex or buy dinner this time etc. That one check frees you from all other obligation. Otherwise it could never be fully about you, the T would start to feel resentment for not getting their needs met. And if there's that much emotional reciprocity it ceases to be therapy...