C, I'm going to go against the tide just for a minute and give one ounce of credence to what your mother said to you. She said your W is being lazy. I don't want to play semantics with you, but from an outside perspective, I can see that, too. Your mother simply isn't the person that you can hear it from. If 25 said it, you'd be much more receptive.
I'd simply ask you what the D decree says about p/u and drop-off? I'd be very surprised if it puts the entire burden on one person. More likely, it says one does p/u, the other does d/o, or that both parties meet at a central location. If that's what it says, why aren't you doing that? You have a history of bending over backwards, sideways and every other direction imaginable in order to not rock the boat with your exW, or you pad it with the excuse that it's "what you want," it's "better for S," etc.
If you were to tell your exW that your current arrangement isn't working well for you anymore, and asked her if she could pick up some of the slack, such as meet at a central location or assume p/u or d/o per the D decree, would she agree to do so without complaint or criticism?
If she wouldn't, then what is your explanation since it isn't laziness? If she would, then why aren't you doing just that? You are still making this too easy for her. You are still providing her all the benefits of a H without any of the investment. You've heard the saying, "Why buy the cow when the milk is free?"
You might consider reading "No More Mr. Nice Guy" if you have time. It's not what you probably think based upon the title.
