It's the policy of the bondsman, not the court. You basically pay the bondsman 10% of the bond in exchange for them posting the rest of it.

Some people skip the hearing, and then the bondsman is out the money, so they keep the 10% to cover their risk.

I don't know how the $50,000 number works - it seems the bond company is paying the rest of it, but I don't know what they get in return.

Interestingly, there are some district courts/jurisdictions that are turning against bail bondsmen for being exploitative. Some will try and outright ban them from operating (either by explicit local ordinance, or by denying them the agreements on standing credit and prisoner transfer that they need to operate), but more interesting are the courts that try and eliminate them via competition.

As of now, bail bondsmen generally charge a fee of 10% of the bond posted, and then use a standing line-of-credit they have with a local bank to pay the bond to the court. The fee covers their costs and the costs of hunting down people who skip bail, and the line-of-credit is what actually pays the bond. To out-compete them, some courts are setting a normal bail bond, but giving people the option of satisfying the bond by paying 10% in cash (which is refunded if they show up in court) as opposed to 100% on credit from somewhere.

Let's say someone is placed on bail with a bond of $100K. Option 1 is to find $10K in cash, use it to pay a bondsman (which costs $10K), and then have the bondsman put up the $100K to get them out of jail. Option 2 is to find $10K in cash, pay it to the court directly, and then get that $10K back when the person shows up in court. Either way, the person is out $10K - but if they pay it to the court directly, they'll get it back.