There are quite a few reasons, but the simplest way to explain it is that home cooks don’t have the same fancy equipment as large producers, and they also don’t add the same stabilizers/emulsifiers/other artificial junk that commercially produced ice cream has. That said, I think I’ve found a hack to make homemade ice cream freeze a bit softer — use reconstituted heavy whipping cream powder! I’ve tried it multiple times now (including in this mint chocolate cookies ice cream recipe and my oatmeal cream pie ice cream, among others), and it consistently yields softer, more scoopable results. As a bonus, it’s also cheaper than regular cream and shelf-stable to boot!