I used to work at a hotel that was arguably the best in town. It was the type of place where people splurged for special occasions like anniversaries and birthdays. On a weekend, we'd sometimes have a dozen people trying to get free stuff from the hotel.
Unless you stayed with us regularly, the only thing you were getting was a "Happy Anniversary" from the Front Desk Representative. As a for-profit business, there was little gained in spending money on one-time guests.
Of course, some people here may see that as harsh. But, remember that not everyone is honest. Birthdays are harder to fake, but there's literally no way for a hotel to verify an anniversary date (without getting into super creepy social media stalking). Dishonest people will lie and say it's their anniversary on every hotel stay.