I have three comments about what you say here.
First, on paratransit. The paratransit service (MetroAccess) in this area is already run by private contractors. And, it appears that they aren’t doing a good job. (See second article down.) The short-term solution, obviously, to create vouchers it in some way and, in many cities (including in Northern Virginia), that could work. The “problem” is that in D.C., nearly all cabs are owned by their drivers, and as a result don’t participate in big dispatch systems, and thus can’t really be called to a specific location (There are cab companies in the phone book but good luck on getting a cab to show up when promised.)
D.C. has this system — which makes it is much easier to hail a cab on the street — because it doesn’t ration medallions or require that all cabs be newish cars. Coupled with a zone-based fare system, this is good for just about everyone unless you want to call a cab to your house. I wouldn’t want to trash it to create a cab system that would work better as paratransit and I’m afraid that you’d have to do just that. Cabs also, of course, are not typically equipped with the wheelchair lifts most MetroAccess riders need. So simply handing it over to cabs would leave some people “high and dry” at least in the short term.
Second, on subsidies. Although all dollars are fungible to some degree, Metro, like all other large transit systems, says that it segregates the money it spends on various parts of the system (bus, rail, paratransit.) Eliminating paratransit tomorrow would not result in a near-equal transfer to the rail division of WMATA.
Third, racial favoritism. You may or may not be correct on this point but I think your evidence is lacking. African-Americans generally work in government at higher than average rates so it’s not surprising that they would be overrepresented in the Metro workforce. Over-representation (and under representation) are facts of life in all professions.
Fourth, is Metro incompetent? The subways are clean, comfortable, and mostly on time. Train frequency could be better but that’s because the system has no bypass tracks. Metro actually has the highest “farebox recovery rate” of any large train system in the U.S. That, to me, seems like the major sign that’s its decently run within the bounds of what one can expect from a political organization. All other cities with large train systems subsidize them more heavily and only one large subway system in the world gets by without an operating subsidy. I’m not saying that no other way exists to operate things: I actually believe that something similar to business improvement districts could probably work to provide ongoing revenue to keep trains running without any true tax subsidies.
In short, I’m not sure that any incremental changes will improve things for Metro. I think it’s roughly as well run as we can expect given its current status.