How about getting a cab between the parks? Say, going from DHS to EPCOT? Is that possible, and where would I find them?
Why?
These two parsk are only a short walk away from each other. About 15-20minutes, depending on your pace. If you are going tothe second park ofr an ADR, I'd allow extra time - but the walk is petty direct and short. These are the only two parks you can walk between, but it makes hopping easy.
If you don't want to walk, then you can take the free shuttle boat. The boat will take more like 20 minutes, maybe longer if your timing is off. The boat makes a few stops along the way, so you could also walk partway and take the boat partway.
You just leave via the back exit of Epcot, between GB and France. It's a pretty area.
Beyond that, in this case, taking a taxi would actually most likely take you longer, as a taxi woudl have to drive the long way around, and would not drop you off directly at the gate. It will probably take you more like 10-15 min to walk from the IG gate to the taxi drop if you walk quickly. The taxi could also drop you off at CR, but that still a 7-10 min walk to MK.
The other parks, well, Epcot to MK (or MK ot Epcot) there's a monorail. It dropps you off at the TTC, but a taxi will also drop you off and pick you up at teh TTC- or one of the resorts. Generally WDW transportaion is about the same as taking a taxi. Even at peak times of day, you usually can fit on the first monorail that arrives. (not many folks head to MK after Epcot closes; they head back ot their resorts.) Leaving MK, you can take either monorail line to the TTC, but the express is usually faster, since it's direct. (You can also take the large ferry boat to the TTC, but it's going to be the slowest of the three.)
Other hops are done via bus. In those cases, a taxi will most likely be a bit faster, but it depends on the timing of the bus. You can get transportation to any park from the TTC, but you can also go directly between the rest of the parks via bus. The only exception is DTD. To get to DTD, you must first go to a resort or the TTC - so a taxi would be quite a bit faster.
If you want to take a taxi formthe parks, just ask or look for signage near the resort bus area. Usually the taxi stand is kind of off to the side of the park exit. Somewhere kind of beyond the bus/tram area.
OP is correct though - one time we usually take a taxi is going between resorts.