It seems like in the last 20 years, though, the "cookie cutter" Bridge designs have been fading away and a new era of "Bridge Personalization" has been the new norm.
When I lived in Ohio and now living in Colorado for nearly 15 years, it seems that most bridge replacements or new interstate bridges being built have had either distinctive parapets, coloring and/or stamping of parts of the concrete walls, or specific designs of the side rails/barriers crossing the roadway, or any combination thereof.
Unless it is a simple crossing of a creek, or a road in a rural area, I don't see much more than a handful of similar styled bridges built in the last 20 years in a single area anymore.
Perhaps the "cookie cutter" style of bridges in the 50s-80s was likely due to the rapid growth of the interstate system and the need to get things built asap.