Welcome to Beemaster!
My question: How do they get so many different flavors of honey? Do they have hives in every one of these locations. Example: orange groves, lavender fields, wildflower fields.
With the exception of wildflower, which as Xerox mentioned is just the term for "any flowers", to get a "flavor" of honey, or a honey produced from a specific nectar, the bees must be working that specific flower almost exclusively. We call this a monofloral honey. So for example, orange blossom honey comes from mostly orange blossoms. This is accomplished by either moving the bees to a location that has predominantly these flowers, like an orange orchard, or simply by the fact that there is a large amount of one single plant in bloom at one time. For example in my area we have the goldenrod and aster flow on right now, and since those are pretty much the only flowers of large quantity blooming that the bees visit, I know my honey is goldenrod/aster.
2. How do they know that the pollen is specifically coming from those sources to be able to label the honey as such?
I sort of answered this in the previous section, but I want to mention that the thing we are identifying is the nectar in this case, not the pollen. Pollen source is mostly IDed by color. There are traces of pollen in the honey, but the bees will store the nectar and pollen separately in the hive.
3. As a backyard beekeeper without access to areas such as these, If I wanted to diversify some of my honey to create unique flavor profiles, could and I and how?
Depending on where you live, you don't need to move your hives to get monofloral honey. In my area, the big monofloral flow is the sourwood flow, which runs from mid-June through July. I don't need to do anything but put supers on my hives to get sourwood honey during this time, because the sourwoods are the preferred flowers for the bees and they won't visit hardly anything else. Just learn about the plants in your area and the major honey flows and the bees will do the work for you.
I also want to mention that honey places often sell flavored honeys. These are honeys that have had flavor added to them, like the honey house near me sells basil honey that has had basil added to it. Honey bees do love to visit basil, but this honey is not from basil flowers, it's just wildflower honey flavored with basil (and it is soooo delicious by the way). Just check your labels when buying honey to see if the honey is a monofloral honey (from a single type of nectar), or if it's flavored.