That is not how real point of sale systems and stores operate in practice. I actually managed a retail chain of bike shops as the Buyer and back office manager. I was the one maintaining the point of sale connections and system. There are always errors in these systems largely due to new and incompetent sales staff that sell/return/enter duplicates of the wrong items. They can enter almost anything wrong, from gender to color, from model year to brand. I’ve seen them all. Connecting these systems online is an absolute nightmare. I tried it with shopify, but has to limit the sku’s to items I could completely control with minimal intervention from other staff. Generally speaking, the POSystem in a local retail store can be more loosely managed where the staff can make up the gaps in mistakes when the POSystem numbers do not perfectly match the local stock. If you want to track inventory like is required for online retail, you need a whole different kind of micromanagement and responsibility from staff. You also need something like quarterly inventory audits. These are quite time consuming and are a total loss in the labor time involved. For online retail to be competitive the margins are absolutely untenable trash for brick and mortar retail. They are not even close. The biggest expenses are the commercial space rent and labor costs. With e-tail, the labor is less skilled and the space is a cheap warehouse somewhere remote. General Retail margins must be 40%+ while e-tail is 15-20%. The two are completely incompatible. This is why real quality brands do not sell e-tail. It has to do with how distribution and preseason wholesale buying works. There is more complexity to this, but overall the two are not compatible. In fact, most high quality brands will not allow most of their products to be listed online except under certain circumstances. This is to keep things fair to all parties and prevent undercutting based on whomever has the lowest overhead cost.