Unfortunately, Clematis, I can top your story: My in-laws NEVER gave us a wedding present AT ALL, much less acknowledged our anniversaries. I didn't ask for a gift of course, but they did mention these two factors to us in conversation: 1. although it was my DH's first marriage, he was 40 and they said we didn't need anything; 2. they had to drive 4 hours to our wedding so they spent some money getting there, although we paid for their hotel room* and everyone else's who came and we had a sit-down dinner after our ceremony.
Either one is no excuse, really. It's entirely up to them whether they want to give a gift but etiquette says when you attend someone's wedding, you should give them something.
*The hotel makes for an interesting backstory. We paid for everyone's room on our wedding night at a mid-grade (Hilton) hotel. My in-laws came for two days. My FIL is the Cheapest Man Alive and although we negotiated a group rate, he thought $100 per night was "too expensive," even though he would have only paid for one night. (Yet, he will drive 400 miles out of his way to go to a Casino and they are constantly complaining how broke they are. But of course that doesn't stop them from buying shit for the grandbrats, particularly my loser BIL's brats, because he's twice divorced and just HAD TO breed with each wife.)
So what do the cheap in-laws do? Four of them stayed in a $59.00 room that was 45 minutes away from where everyone was staying. They ended up paying a comparable rate because the hotel where they stayed charged them for the additional adults. Way to save $ there, Dude, not to mention the gas and inconvenience of packing up and moving after each night.
I can't complain about my own family. I get birthday, Christmas and anniversary cards from them, plus a healthy check for each occasion. My relationship with my own parunts has become better over the years because I have time to spend with them and once it became apparent that the grandbrats are incapable of writing a thank-you note, no matter what the gift is. (Shame on my sisters, who were raised better than that.)
So my situation is different from yours because it's DH's family who don't do anything. So really, I just keep my mouth shut. When I got into this marriage, it made it clear to his family that I am not social chairman. Too many wives will pick up the slack and send cards and stuff to their husband's family, but that's not my job--it's his. So I tell them to talk to him. Not my battle.
But I have mentioned to DH that his parents should be kissing the ground he walks on. He has always been a good, dutiful son, (thank Todd they live 800 miles away) and he's been self-supporting since he was 22 years old. Unlike his jerkwad siblings, like the aforementioned BIL, who is on a heavy dose of economic outpatient care from his parents because he was too stupid to use birth control and control his family size to what he could afford.
But Clematis, since it's YOUR family, I would address it with them when your DH is not around. You could say something simple, even in a lighthearted, humorous way..."Hey, Mom, ever notice how I get calls expecting me to be at the sproggen's birthday, yet nobody remembered it's our anniversary?" You may want to cut back on the gifts and let them know why. If they are jerks, they'll be pissed but who wants to waste the $ on greedy jerks?
It's amazing how many non-childed get shit on by the breeders in their family. I myself spend more time with my parents, including taking care of elderly relatives, because my childed sibs can't be bothered.