They are within existing mechanics. The PhB explicitly says grapple and shove are not exhaustive. Players can take skill or stat contests to achieve effects. That is in the rules of 5e
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It’s adjudicated by the DM, but so is everything in 5e.
If you’re frustrated that you don’t have options in combat first look and see if this is an element in your game. If it isn’t maybe think a bit more creatively.
Casters aren’t as good as martials at these abilities because generally they don’t have the athletics or acrobatics to perform them as well. Neither can the benefit from the follow up attacks you can take afterwards.
So the wizard uses mage hand to throw sand in the Orcs face (debatable as it could be considered an attack). Then what does he do to follow up? Go toe to toe with shocking grasp? Mage hand has a 10lb limit which seriously cramps your style when flipping a table.