You're correct about the Move & Attack action; it doesn't say "exact" because how much Command you have to spend depends on how far you're moving. But this particular rule also refers to the Research & Build action (which shows a resource cost of goods, power, and money), the Card Action or Diplomacy action (which shows a resources cost of cards and power), and the Recruit action (which shows a resource cost of money). All of these action spaces show resource costs but don't say "exact" because the amount of these resources that you have to spend depends on other factors. The only spaces which say "exact" are Scavenge (1 Command for any action) and Any Action (2 Command). These are the only spaces with exact costs (although there may be additional costs afterward, depending on which action you choose as your "Any Action".)
Thank you for this confirmation.