Can a slow cooker meatloaf get a browned crust?
It's very difficult.  The trapped moisture can keep the meatloaf from drying out sufficiently to brown well.  ... but if you vent the steam, you're also releasing a lot of the heat, so it might cool off too much.

I'd personally try turning up the heat to high and leaving the lid askew for the last 15 minutes or so of cooking, and see if that gives you the desired effect.  You may also want to remove some of the liquid (but not all, as it'll help to regulate the heat and prevent the bottom from getting too far overcooked)

I suspect that the laws regarding 'food styling' as it applies to recipes in magazines aren't as vigorous as for advertising a product they want to sell you in stores or a restaurant.  (where they have to use only the same techniques and ingredients as what's being advertised ... although if it's for cereal, they don't have to use milk ... and if it's pie, that doesn't have to be real ice cream, etc.).

If you just want it 'brown', then a spray of soy-sauce will do it.  If you want it actually 'browned' (ie, with an actual crust), you can take a propane torch to it.  (although I'd do it out of the crock pot -- ceramics don't take well to high heat from one side only)