I am not sure where you got your Tax Cost Ratio, but if from Morningstar.com, the numbers are incorrect for many investors because the assumptions that morningstar.com makes do not apply to those investors.
But your point is well-taken: Some index funds are more tax-efficient than others even if they follow the exact same index.
For those that want a more detailed analysis for their own personal tax situation, please see:
https://www.bogleheads.org/forum/viewtopic.php?t=208818
And some folks would rather use a Fidelity fund even if it cost them 0.05% more in taxes on the value of their holding.