To be fair to the US Shuttle, it was in srvice for 7 years before Burn's maiden flight so it's hardly surprising Buran had a more advanced design and in particular more capable computer controlls. The article also doens't mention the actual reason the STS orbiter carried the main engines - so that they could be re-used. That may not have actually panned out in terms of saving costs, but it's important context.
Simon Hibbs