What is up with the cancelled items?!

GBrunner321 thought this was worth mentioning said

I think meh and it’s companies might need a better inventory system. I have now had 3 orders (not related to the meh-rathon) that have been cancelled because they ran out of stock. This is, of course, after my credit card has been charged so I now have to watch to make sure the credit gets put back on.
Clearly I buy too much but this is making it a hassle to keep track of my orders and charges!