Surely, the value of a successful marriage is many, many multiples what a dating app might charge. And surely, a dating app that successfully pairs people into high value marriages will recoup any losses by earning new customers through the word of mouth recommendations.
I don't think you can extrapolate the case for a dating site to all businesses, especially to cases of tangible goods. A car salesman doesn't make a dime until I buy a car.
Dating sites are an interesting business because a happy customer is one that is no longer using their product. So how do you monetize that?
If you charge a one-time up-front cost, and a paying customer uses the site for months and never has success, then you end up with a disgruntled customer.
If you charge a monthly subscription, then you get a perverse incentive to not please your customer, or only please them enough to keep paying, because as soon as they enter a relationship, they stop paying.
Only charging after some sort of measurement of success (Like marriage) would be impossible to enforce.
Give users an option to put $1,000 in limbo. The condition being, if you date/marry someone for 2+ years that you met on the app, the app gets to keep that money.
In return, you get a badge on your profile. It's a certified stamp that your "money is where your mouth is" and that user either as plenty of disposable income, or is intent on long term commitment.
^ Both are positive signs for the prospective market.