Unfortunately, in many cases the constraints [on the options being considered in a study] ... are not imposed by the decision-maker (especially in political systems where much of the authority is distributed), but imposed by outside actors, who may be engaging in self-aggrandizement or rent-seeking at the expense of transit outcomes, but whose participation is needed for the project to get done.
And in many cases, such folks don't want their fingerprints on the planning documents--you won't ever see an Environmental Impact Statement [EIS] explicitly stating that [bus options weren't] considered for project X because developer Y would withdraw his support for the project causing his ally councilman Z to vote no; or conversely that governor W is a teabagger who considers rail transit to be a Soviet plot and thus BRT [Bus Rapid Transit] was the only rapid transit option to advance out of the [Draft EIS] phase in order to avoid a veto. These sorts of political decisions are made in the backroom, off the record, and then often justified on an ex post facto basis when the stench gets too bad. ...
Reputable consultants ought not take work that involves declaring that night is day, in an attempt to paper over a blatantly bad political decision. However, in situations like just described, there is plenty of work for reputable consultants to help transit agencies to make the best of a bad situation--if the political realities of a situation require that agency A implement a transit network using only mixed-traffic streetcar, and that other modes are off the table, a good consultant will help them design the best streetcar system that lies within their budget.
At the risk of misquoting Jarrett ..., sometimes this is what "help[ing] you implement your values" really means. Often times the "values" in question aren't the values of the riders, the community, or the sponsoring agency, but those of the powerbrokers who ultimately control the fate of the project in question, and who may have little actual interest in improving mobility.
As a consultant, I really like working in situations where the key players really do want to explore the options and reflect the community's values. Having said that, I don't think there's a experienced transit planning consultant on the planet who hasn't been in situations like the one Scotty describes.
Especially in big, complex urban areas, you work for your client agency, and your client agency answers, sooner or later, to elected officials, and if those elected officials aren't happy, the consultant is likely to be blamed. So yes, in an ideal world, the elected officials are conduits for the aspirations and values of the people. But if the elected officials decide to reflect somebody else's values, well, they still get to decide, so yes, it's about their values.
Some purists decide that whenever someone talks about high ideals such as reflecting the values of the community, but then works in real situations where other objectives are taking precedence, that person's being hypocritical. There's some validity to that. At the same time, we all have to move between idealistic and practical modes of thought. You may feel that what company X is doing is ethically wrong, but while you fight that you still have to live in a world where company X is doing that. It's one of the harder things that humans are asked to do, actually, because we do want, in varying degrees, to feel pure and consistent, so we feel awkward about working inside a situation that we know, in larger terms, is somehow wrong.
I've thought about this a lot, because one common critique of me as a consultant, at least in my errant youth, was that I often talked about ideals at moments when everyone in the room needed a practical focus on the current political situation. In middle age, I'm better at working in whatever situation I'm in, but I still feel the awkwardness, and in fact I value it. So long as I feel uncomfortable about the real-world situation, I know that my adaptation to the situation isn't undermining my ability to hold, and act on, clear ideals. Only if it felt easy would I start worrying.