I can easily believe that finding LZ's can be hard, big time, especially at night. It's one thing to fly an instrument approach to a facility (airport) that is well lit, extremely well documented, and often has electronic navigational aids available. Now, do that at night, in bad weather, to a LZ that you have never seen before other than on a map, that does not have any sort of documented instrument approach, with the possibility of unknown obsticles / wires, trees, towers, and without purpose-designed lighting -- and oh, by the way, knowing that it is often a literally life or death mission -- so you are motivated to accomplish the mission....
The Trooper 7 pilots *really* like using the CRE airport for these reasons -- they know where it is *exactly*, know there are not any wires or other obstructions, it's lit at night, has lit wind direction visual aids (windsock), has decent access for the ground crews / EMS. Beats the heck out of a ball field or a parking lot! Overall a very much more safe aircraft operation to fly into / out of an airport.
The MSP pilots are some of the best in the business, bar none, I know a number of them personally. Talking to them they have relitively recently modified their LZ and weather minimums, in part due to the specific mishap in bad weather near Andrews about 18 months ago. Also, the NTSB and FAA have been looking *hard* at HEMS operations due to a nationwide trend of increased mishaps in the last few years, and has made a number of specific recommendations regarding landing sites, weather minimums, training, and maintainence. Better pilots than the MSP guys? There aren't any. Anywhere, for any wages. They do good stuff, daily.