I don't think the "minnows" you see under your lights, are actually "minnows" (as in the baitshop kind). They're usually Shad, with the occasional Silversides ... at least they are on most lakes I've fished.
That bait net probably wouldn't get many Shad or Silversides .... they're pretty fast :p
BUT .... if you ease along the bank at night, with a light hanging over the side of the boat (towards the bank) ... if the light is followed by several pencil shaped "minnows", you could probably dip those up with that net. Those are Silversides ... and one of, if not THE, best Crappie bait going
You're not likely to catch Shad in it though ... you'd probably need a cast net (plus a circular bait well/bucket & aeration).
You might be able to get some creek minnows with a net like that ... but, even it would have to be shallow. A seine does a much better job, if the water is much over knee deep.
I think the primary purpose of that "bait net" ... is dipping from a "cement pond" :D (aka - baitshop minnow tank).
... cp