The reason the Fly and Levitate spells are called out specifically is that they magically hold you up. You can't choose to fall while under the effect of those spells without dismissing the spell.
A creature with wings, on the other hand, can fold its wings and effectively stop flying and start falling.
Given that mecha flight is accomplished by thrusters that can be turned off (and turn off automatically at the end of movement unless you have an upgrade/ type of robot that has a full flight speed) they would seem to fall into the latter category and not the former.
On the RAW side, "effect" in that context is referencing flight as an SLA or supernatural ability. It's not trying to say that all flight is the same as a fly spell.
However, this DM ruling territory and it won't even matter unless Scout89 decides he wants to take the feat so let's table this discussion for now.