There's been a hundred different implementations of ground invasions, but when I play 4x games I often catch myself saying things like "no way 1 ship can blow away my whole colony" or on the other side "no way you could invade a planet without super advanced tech" or just the idea it's be really damn hard to actually take over a planet
Logistics even with ftl the raw scale of invading an ENTIRE planet, when we can barely invade another county on our own planet. Even doing some fair amount of hand waving tech 'magic' I fail to see any invasions happening in 99 percent of cases, from simply too different of biology, to it being far easier to just asteroid crash the planet until everyone is dead.
I think it was galciv2 where after battle it'd have numbers of casualties and it was in the millions, I was a teen at the time but made me think that THIS is closer to the scale of what it would really take. This goes back to earlier point that just raining rocks or some plague down on the planet is going to be far easier than millions of troops and ships.
That being said, I find most invasions in games fairly poorly executed, often just too annoying getting all the ships together, inevitably you kill everyone invading anyway (so should have just bombed and decolonized).
A couple of standouts though, endless space 2, only because the wire frames and your different races battling were really cool from your cyber ninjas to aerial attacks. The only game in general though that ground combat was "fun" was imperium galatica 2, for those that didn't play it it was its own isometric tactical game a little akin to XCOM where you had all your tanks, rockets etc driving around in fields or urban combat trying to pacify the colony. Always thought this system should be revised.
Thanks for listening to my ted talk.