Hiring managers are well aware people's primary motivation for work is pay and that the question is bullshit, but are directed by their superiors to find applicants who are more enthusiastic to work for them, as they're likely to work harder and for less. Look at the video games industry as a prime example. Many many studios and publishers hire developers and pay them beans because people are lined up around the block to work their "dream job" in the games industry. Those same developers could likely get a job in some other industry making software for something boring, but for far greater pay, benefits, work/life balance, etc.

I am in agreement that not being able to be more upfront with employment motivations is troublesome, but our choices are either play the game, find an employer who cares less about the corpo garbage, or self-employ.