@WhataPlaice don’t feel you need to read this, I got carried away!
There’s an International Code for Botanical Nomenclature (and an analogous one for Zoology) to make sure names are consistent, not duplicated, etc. The ICZN has a team who spend their time checking newly published names, so I presume ICBN does too. Then it’s up to peer review to see if any names make sense botanically, eg someone will publish a paper to say that for example, buttercup, Ranunculus, isn’t a single genus, it’s two groups which should be in separate genera. They’d refer to the Code to see which of the groups hung on to Ranunculus, and give a new genus name to the other group. Then they publish, and if they’ve made their case well, the name sticks, and the rest of us grumble that Lesser Celandine has changed from Ranunculus ficaria to Ficaria verna. (ICBN doesn’t allow Ficaria ficaria, whereas the zoological side is full of them, Bufo bufo, Martes martes, Troglodytes troglodytes etc)
At the end of this you may quite reasonably say “why don’t we stick to common names if the scientific names keep changing?” The reason is that scientific names are trying to reproduce the “family tree” of species, so they tell you a lot more than the name, for example, whether you’ve got a reasonable chance of hybridising two species or grafting one on to another, what their preferred growing conditions are like. And they’re in a common language so you don’t have to remember that Muguet de bois is Lily of the Valley, or that Bluebell is a spring flowering bulb in England but a summer flower herbaceous perennial in Scotland.
We’re having lots of changes inflicted on us at the moment because DNA studies are a lot better at sorting ancestry than looking at physical characters.