At 400usd your going to only get a BD or big box road bike, or one without gears. It will most likely have a steel frame or if your lucky, aluminum.

The components will be entry level. The seat won't be comfortable, the tires will be cheap. The rims will be machine built.

At 1000usd you can have a high end aluminum frame with carbon fork and mid tier components, better wheels, better tires and peace and peace of mind.

You can easily also buy a used carbon framed road bike for 1000usd.

With either of the latter two options you get quality components, you won't get that from a 400usd bicycle you bought from Walmart.

Peace for mind, knowing your riding a quality machine that won't require as much maintenance.

My Giant road bike can beat the poop out of any ss and Walmart commuter I see, over ten miles I can beat then by five to ten minutes.

In ten minutes I can cool down, lock my bike, change shoes and get ready for work. Meanwhile the beater commuter is just barely showing up.

My commutes have been 5-10 miles one way, plus I ride the same bike on the weekends.

That is another point, a lot to find American commuters ride the same bike on the weekends that they ride to work, they don't need two bicycles. It is more cost effective to buy one nice road bike and ride it to work as well as group rides.