Outcalls: you have the expense (time and money) of travelling.
Incalls: you have the expense (time and money) of the place.
Which one of those is bigger depends on how many people you're seeing - if you aren't seeing many, the 'per client' cost of an incall place that's not your home can be considerably higher than the cost of outcalls, for example.
There's a time cost to doing incalls too, because you either have to get there or you have tidy the place up...
As ever, there's lots more about the pros and cons here, if you search for it.
At least one person here used to ask for ID when doing hotel incall days. She had the advantage of having a good reputation and very good marketing, so attracted people who wanted to see her, rather than 'someone'. The more people want to see you, rather than 'someone', the more you can ask of them.