This is arguably rightfully so, as a well thrustered flying craft has full six degrees of freedom in its movement, including when its digging, whereas ground vehicles are generally limited to maybe 3 degrees of freedom for movement, and come with numerous downsides as one might expect when comparing to a perfect floating brick. This presents an engineering challenge of which i've had many solutions, but no matter how fancy, or how mobile, or how well engineered it is, it can never seem to beat a flying miner. I've found that the deepest ores, on earthlike seem to be about 100m deep, not including the size of the ore vein. This behavior however is quite unsuitable for MP, simply because there is absolutely 0 benefit (game mechanically, personal satisfaction doesn't really pay the bills) to actually engineering a somewhat advanced solution VS just making a thruster porcupine with a couple drills strapped to the nose. So we've got a bit of an idea how I like to play, this is great for single player, as you can work at your own pace and generally speaking aren't in any kind of rush to get stuff done. See below for a small grid crane and trailer truck that can side load about 70 tonnes at max extension. This includes clang, simply because I don't have much of an issue dealing with it. Now, lets also assume that there are no real bugs that would spoil this gameplay, as discussing stuff around bugs is stupid. I honestly don't bother leaving planets just because i love the tougher gameplay. I have a great soft spot in my heart for ground based vehicles in this game, they're fun to design, balance (sometimes literally) and try to make it as close to "real" as i can.
Lets just assume space doesn't exist for a moment here because its basically free infinite resources that are easy to extract, i'd like to focus on planetary mining.
So, i'll preface this a little bit with my own personal experiences, and maybe some designs. As the title suggests this is a thread about mining in space engineers, We've had a few conversations in discord with various people on the topic, but that quickly gets lost to the void of endless meme spam and people asking why features are missing (tongue in cheek, sorry)