Thanks, Toni!
I'm going to use your idea except with a different sized containers. Large for mixes, small ones so I can fill houseplant pots... I try to use a trowel but most of the time I wind up just using my hands.
Something that will make this idea a great use is for when we have mix "recipes". You know: one part soil, one part compost, one part perlite as an example. The scoop would make easy work of that as we don't really know or care exactly how much "one part" is. I often just use a small 3-4" pot a plant came in but many times they are too thin/flimsy to scoop enough at one time; and if I pick up a larger pot it is sometimes too big to fit in the bucket I keep ingredients in.