Wouldn't combo be more expensive? As there is increased risks to travel agents. Flight+Hotel is considered a package and you have to provide, replace or refund both if one falls through.
The difference with tourism is that usually they are not refundable or have quite limited refundability and these all thus sold for less.
Tourists are typically more price sensitive, so airlines look for ways to sell cheaper flights to tourists while still charging everyone else more. Package deals are one way to achieve that
The difference with tourism is that usually they are not refundable or have quite limited refundability and these all thus sold for less.