A friend tells me about an Australian shoe retailer that instituted a new policy in their store: if you try on shoes in the store, but leave without buying anything, they charge you a fee of $50.

That's one way to do it. I'm never adverse to the idea of a business firing a portion of their customers, particularly the 20% of them that are probably taking up 80% of the businesses time or money because they're very high maintenance.

It will have an effect...but probably not the desired one. The problem here is that this store doesn't know which customers they're punishing. It will keep lots of people away, to be sure, but it's hard to distinguish people who are trying on shoes at your store and then running home to buy them online (which is dubious) and people who wander in, try some shoes on, but don't buy anything on that particular day.

Online commerce is little more than a substitute for traditional retail. But for people who are price shopping, buying stuff online makes more sense. 30 years ago, if you owned a small shoe store, you would probably get some business if you had a decent location for your store. Substitutes change things. It's no longer enough to just have a store, and hope that people will understand how important your business is and support you simply because you exist.

The goal should be to make yourself more appealing and the online substitutes less appealing. Taxing the casual browsers in your store has the opposite effect.