The 8 GB versions are mostly just there as a marketing trick. They know you need 16 GB and they hope that once you get to the order page, you’ll be committed enough to spend the extra cash. You probably wouldn’t spend the extra money if the base config had what you needed. They get to use the lower price for marketing while knowing the model you actually will buy costs hundreds more.
The 8 GB versions are mostly just there as a marketing trick. They know you need 16 GB and they hope that once you get to the order page, you’ll be committed enough to spend the extra cash. You probably wouldn’t spend the extra money if the base config had what you needed. They get to use the lower price for marketing while knowing the model you actually will buy costs hundreds more.