Why do we ground radios?
Often we don't actually ground them, but the ground symbol is just a design convention.  If we had to ground them, then we couldn't have radios in aircraft or spacecraft or make portable hand held ones.
The conceptually simplest radio antenna is a dipole, which consists of two wires running in opposite directions, operated in opposition to each other.  Often these are horizontally oriented, but they can also be vertically oriented.  You might have seen a variation of one on an old FM high-fi receiver, or at least a setup with two telescoping antennas that open out into a sort of &quot;vee&quot;, or a whole series of dipoles of varying length splitting off a common beam in a yagi-type TV antenna.
It turns out though that if you take a dipole and split it in the middle with a big conductive plane, then you can remove one half and drive the plane instead, and the missing half will be &quot;mirrored&quot; by the plane.
So we can take a vertical antenna and set it above a big conducting plane - eg, the ground (possibly reinforced by a spider of wires to improve conductivity) and use that instead of trying to stack one tower on top of another with an insulator in between.  This is actually commonly done, for broadcast and ham radio type installations.
But especially at high frequencies, we can also use a single antenna half above a sheet or chunk of metal instead of the ground - for example, a car, or a cookie sheet, or even the body of a handheld radio.  Think of it as a counter-balance; the term counterpoise is literally used.
So sometimes we ground a radio only in the convention that there's a side of the antenna system (or radio circuit, or even non-radio circuit) that is conceptually ground.
And sometimes we literally put a stake in the ground, and all that half of our antenna.
And in the realm of &quot;serious&quot; installations of radio and many other types of gear, there are also other roles of ground.  For example, it's not uncommon for the housings or radio equipment to be grounded independently of an antenna system which may or may not involve actual ground.  Then there may be a safety ground through the power mains (which would typically go to a ground rod somewhere near the service entry), the grounds of lightning protection systems, etc...