Its probably too creepy in terms of privacy to detail how it works which in turn will give themselves PR. I can only assume it uses arrays of cameras and sensors with deep learning. Glorious amounts of tracking data.
If one day all the stores are like this, I guess you may argue I can still grow my own food, and everything is fine.
By "personal data", if you mean the video footage of your shopping, then it will probably be deleted after a few days/weeks. It will just be used to train (reinforce) the machine learning model, and will be discarded eventually. But your shopping history will always be there, as it is now in online shopping sites...