That is impressive but not impossible. I heard a story (that I believed based on the details of story) about a dealer in CT that I believed to be reputable, that just sucked the fluid out of the reservoir and topped up with new fluid. Now I'm wary of anything the dealer (or any mechanic) does that I can't visually confirm.

That being said, with a lift and air tools, it's not unreasonable to assume that they did pop the wheels off and pressure bleed the system. If you're ever unsure about a shop, you can do a little test like etch the bleeder and caliper and check after to see if the marks still line up. If they pass a little test like that I'd be inclined to trust them a more in the future.

__________________
2012 X5 35D - EGR delete and Stage 2 tune
2003 M5 - Imola/Caramel, Dinan S2 suspension, Alpha-N tune
1990 M3 - CF Airbox, Alpha-N, Schrick 284/276 cams, VAC S2 head, full GC suspension
1991 M5 - Black/Black - stock
1991 325iX - Winter beater

Retired: 1999 328is 5MT, 1994 525i 5MT, 2003 530i 5MT, 2012 X3, 2006 325i 6MT, 2001 M5