why don't shops ever have what they advertise?

[Max]

Here in Australia on websites of various stores they don't have the products advertised on the website in store. Why? Also they sometimes have the product but it's way more expensive than advertised. Thanks in advance

[Jake]

"Don't ever" may be an exaggeration.

Some retailers, including grocery stores advertise "loss leaders" at or below cost that are designed to bring people into the stores where they will also buy profitable items, often these items are in 'limited' supply that in some cases sells out in minutes.

Bait and switch is another related term, in which they find various excuses to sell you something more expensive than the advertised bargain, including it being out of stock.

these relatively small ethical violations are not worth the time of the authorities ti prosecute.