Here is one group of economists that understands the problem with Buy-America policies. In their paper The Political Economy of Public Bus Procurement: The Role of Regulation, Energy Prices and Federal Subsidies, Professors Li, Kahn, and Nickelsburg report that the American bus fleet is more expensive and more polluting than that of other countries:
This absence of international trade has multiple implications. First, the absence of international competition likely leads to high prices. This could result in fewer buses due to capital constraint and hinder the economics of scale that is vital for public transit (Morhing 1972; Parry and Small 2009). While it is difficult to construct a hedonic bus price regression where we control for key metro bus characteristics, our research suggests that measured in comparable units, buses in Tokyo and Seoul are half the price of U.S. buses and buses produced in China are even cheaper. While cynics might question the quality of China’s buses, it is notable that wealthy and well governed Singapore is importing buses from China.
In the absence of international competition, U.S. tax payers face a higher price for subsidizing urban bus services and U.S owners of the domestic firms that produce the buses gain some monopoly rents. There is a fundamental asymmetry in that a small group of domestic producers benefit from the absence of imports while the costs borne by tax payers are broadly spread out (Stigler 1971, Becker 1985). Based on data from 1997 to 2011, the average price for a U.S metro bus (in year 2011 dollars) was $309,000 with the 10th percentile of the empirical distribution being $104,000 and the 90th percentile at $497,000.
A second implication of the absence of bus imports is extra energy consumption and hence greenhouse gas emissions. The bus fleets in Seoul and Tokyo are both more fuel efficient than in the U.S. The fleet fuel economy of buses in the U.S. was 3.54 miles per gallon (of gasoline-equivalent fuel) in 2011, compared with 4.74 in Tokyo which also operates a diesel-dominated fleet of about 1500 buses. In Seoul, the average fuel economy of 61 diesel buses was 5.05 and that of 7,469 CNG buses was 4.04 in 2011.