Many providers don't have cars, and even if they do, some don't feel comfortable driving themselves to outcall appointments. They charge for uber or drivers/friends who take them. And they charge for the time they spend getting stuck in traffic. Many providers also consider outcall to be riskier.
I would be surprised if either party enjoyed driving to an appointment. I know when I drive in areas I'm not familiar with, it makes me nervous, and I'm dependent on my GPS. I would think trying to read paper map to determine street names would be more dangerous than texting and driving...
On the flip side, I've seen providers charge more for incall too. A girl I really enjoy seeing in another city basically can't accommodate me for incall. She has 2 kids who live at home and rents the house with her brother and cousin, among others I believe. There's almost no opportunity for her to 100% guarantee our privacy during the time slots I'm available. If she got a room at a hotel, I'm sure she'd be charging me over $100 extra for incall too.
I refuse outcall unless I have a hotel room for some other reason. Total hassle of booking, leaving a record of my name, checking in at the front desk, and showing up ahead of time to adjust the room AC, lighting, etc... Plus having a stack of room keys left over in my car got old really fast. I don't risk NCNS by providers anymore, I've found most to be too unreliable for that.