Techni-HOs are specialists, usually in some skill or knowledge that we ourselves have no access to. You can expect the HO to do things that you can't ask your spouse to (am I taking this analogy too far?). You seek them out for the specialized services, they perform that service to SPEC and move-on. You don't need to convince them to perform that role, they don't need to be coaxed into acting on your requests. They are PAID to service and they do.
There are Techni-HOs in nearly all specialties available in all areas, making them highly portable. While finding staff to fulfill these rolls in far flung areas is a very expensive proposition. The Techni-John can have a HO in every port, who they wine and dine only when in town (some nylons and chocolate for every port). If there is not Techni-HO in the port we pay a small premium to ship one there short term. There is no expensive upkeep for when not in use and ultimately it is cheaper than having staff in every port.
If we find that we can't support the Techni-HO any more in the area then we just don;t sign them back up for a contract. No painful separation, no legal issues, simple sweet, expendable. And easy enough if we wish to re-engage, they are typically ready and able. Grateful for the new work. A full time resource would not be so kindly if benched for significant
Culpability is one of the most highly overlooked of these values. A well thinking manager who brings in contractors is ultimately in a no-lose situation if played right. If the contractor are successful then the manager who brings in the Techni-HOs can take credit for seeing the solution and implementing the solution. If the Techni-HO is not effective in resolving a situation, then the manager has the solution of getting rid of the problem (in this case the contractor) and therefore can still be credited for solving the problem. If we used internal resources we could not treat them this way without significant backlash.
Techni-HOs fill a very important need in the technical world that we cannot always look to our home grown talent to supply. So don't dismiss the use of Techni-hos it is beneficial to you and your team that you have this valuable asset available in your bag of dirty tricks.