In the end, you get what you pay for. Tide has incorporated technologies providing cleaner, fresher, more stain removing and whitening properties than its competitors. Net it costs more. P&G also has detergents costing less, like Cheer and others with significant cleaning power and other properties. The important thing for intelligent shoppers to know is: "Don't be fooled by the size of the container, particularly for liquids". Many of these generic/store brands are filled with MORE WATER and LESS SOAP. Although they say 115 loads, etc., you need significantly more of such product to get the same results. One can get the store brand results with say a Tide, by simply using less detergent than recommended, i.e 1/2 or less. The same concept holds for toilet tissue and several other products.
In these difficult times, the cost factor is pursuasive until you see and appropriately value the differences. Nothing to beat yourself up for unless you ignore the facts.