Google and Backblaze are not typical enterprise deployments. Each company has built what is effectively an entirely in-house proprietary SAN with a large dedicated team to maintain it. Regular enterprises, ie people who are not in the storage business, cannot do this.
FYI 15000RPM SAS drives will provide significantly more IOPs per disk than 7200RPM SATA drives. Depending on the application, that may be important. The firmware on SAS drives also tends to be tuned for heavily random workloads, and for operation within a RAID array. Cheaper SATA drives come with a shorter warranty and conditions on how frequently they are in active use. Outside of these, yes the drives are essentially the same.
I suspect SSDs will eliminate most of the remaining business case for deploying SAS drives in the near future as the cost per gigabyte continues to fall.