A lot of store sales are by browser coming in and making impulse decisions. Customers buy things that were not even on their mind when they got out of bed. An admissions fee would cost them a lot of sales IMO as potential impulse buyers would not enter. A better solution would be to give out coupons for say 5% off with a short expiration date.
Walmart is probably the worlds most successful retailer. Utilitarian low profit items such as toilet paper,soda, milk, other staples are deliberately put in the back of the store so the customer has to walk through a rat maze of aisles and see impulse items such as clothing, jewelry,etc to get to what item they came in for. Often the customer walks out with extra items he/she had no intention on buying. An entrance fee would simply keep people out of the store and sales would be lost. Many other retailers follow this strategy. They often also rearrange the store for the same reasons. They do not want the customer to come in, get a quart of milk and leave without being exposed to other items.
Dale H