It's just a monetary conversion and it's in their style guides. How much is "millions of euros" in dollars? Answer: "millions of dollars".
If they'd said "it's estimated to cost 1.5 million euros", they'd have added "(1.7 million dollars)". But since they didn't have a specific value, they just used the units.
If they'd said "it's estimated to cost 1.5 million euros", they'd have added "(1.7 million dollars)". But since they didn't have a specific value, they just used the units.