That's because their retail price doesn't reflect the externalities. Cheap subsidized water makes them much cheaper than if the farmers had to pay a fair price.

Ground beef - all meat, really - is a luxury food.

Beef also uses a ton of water, probably more than almonds.

Sound like they would be more expensive if the farmers didn't have such advantageous water rights.

Because the farmers don't have to pay for the water they use...

More like 3-4 x as much.