Many of the roads/bridges and specially the HSR built in recent years have had little return.
Every economic activity is not strictly about the relationship between types of capital and all supreme profit. That's only one of the perspectives among several others. It'd be fair to say financial analysis mostly deals with above relationship in details and identifies the relationship among those elements and quantify the all important, for them, profit, which I believe is your line of argument. Here, an economic activity is only a means to an end, ie ,profit. You can also look at an economic activity from production, distribution and expenditure perspective, where an economic activity is only a means to further productivity, meaning they are intermediate inputs to further economic activities, not strictly for profit only that ends in that stage there and then ; basically the same way how Fed's stimulus works, except in this case, stimulus money wouldn't go to Wall Street and Corporate fat cats and capitalist cronies. Here, you try to count the benefits it brings to society in general, not the profitability, but the maximum productivity and fair social equity and justice. Here, 'why' of the economic activity is more important than "IRR". That's the proper frame of reference for you to understand why, not one dimensional business journalist articles that were written in such a way so that the regular average run of the mill joe journalist who wrote it in one dimension without much thinking or thought process would get his pay, despite the obviously different characteristics and goals of the different economic activities.
If you still cannot wrap this idea around your head, try picking up Fed's mandates, any laws on taxation, social and infrastructure programs in US etc., etc., so that what you are thinking and saying can move on to 21st century.