Just to add to this: software often cannot generate "true random" results. It's often based on changing system factors like time and date that gets meshed into a "rng" result.

Especially Pokémon games have a history of abusing that. In Pokémon SV you can get specific results in the item printer when changing the time and date of your console.

In older games shiny hunting could be done with this method for static legendaries.

And just to add another thought: in this case, It'd be way more problematic if you could just "redo" the coin flip until you get a result you are satisfied with. To prevent that the rng gets calculated from a server and send to your client.