What people want is highly relevant. Planners can try to nudge people along, or even foreclose options in attempts to channel behaviour. And people can still find ways to opt out. Worst case, money spent becomes a sunk cost with nowhere near the anticipated benefits. Example: a lane of traffic conceded to bicyclists which bears a tiny fraction of its former human traffic.
Obviously anything government does that meddles with what people do is government intervention. Much of what government does is intervention aimed at changing the way people behave. The fact that people are working within and around earlier intervention doesn't mean that change now is not more intervention.
The people are multitudes, and they can not insulate themselves from failure the way governments and planners can. So there are thousands of trials of ideas, and failures become evident and are discarded quickly. Governments can only try a very, very few things (and often enough just pick one for ideological/political/social aesthetic preferences and stick to it) and are terrible at cutting losses.
It's easy enough to predict what happens. A set of objectives are identified; some initiatives are undertaken to achieve the aims. The value of the intended objectives are accounted, as are whatever aims are achieved. The opportunity costs are never measured and probably not even considered; the unforeseen consequences and shortcomings are blamed on "market failure".
An example of what planners and politicians do: City of Kamloops will (apparently) spend $5 million (matched by BC for $5 million more, if I understand) to construct a pedestrian overpass about one-half block from a major intersection with pedestrian controls. This would be for the benefit of a few hundred students, most of whom are unlikely to ever be Kamloops taxpayers, living across the road from TRU. If that's the best they can do, they ought to just turn the money back to the province and to the municipal taxpayers. They aren't even trying to be smart.