Can you explain why the United States hasn't adopted high speed trains for mass transit?
The United States has not adopted high-speed trains as a mass transit option for a variety of reasons. These include a lack of political will, high costs, and existing infrastructure and cultural preferences for car travel.

Lack of political will: One of the main reasons why high-speed trains have not been adopted in the United States is a lack of political will. Unlike other countries such as Japan, France, and China, which have invested heavily in high-speed rail networks, the United States has been slow to embrace this technology. One reason for this is that high-speed rail projects require significant government funding and support, which can be difficult to obtain in a political climate where infrastructure spending is often viewed as a low priority.

High costs: Building high-speed rail networks is expensive. This is especially true in the United States, where the distances between cities are often much greater than in other countries, and the cost of acquiring land and building infrastructure can be high. For example, California's proposed high-speed rail project has been plagued by cost overruns and delays, with estimates for the final cost ranging from $98 billion to $118 billion.

Existing infrastructure: Another reason why high-speed trains have not been adopted in the United States is that the country already has a well-established system of highways and air travel. Many Americans are accustomed to driving or flying to travel long distances, and it can be difficult to convince them to switch to high-speed rail. Additionally, the existing rail infrastructure in the United States is often outdated and in need of significant investment, which can make it difficult to build high-speed rail networks from scratch.

Cultural preferences for car travel: Finally, there is a cultural preference for car travel in the United States. Many Americans see driving as a symbol of freedom and independence, and there is often resistance to public transportation options that require them to give up control over their own transportation. Additionally, the automobile industry is a major economic force in the United States, and there may be resistance from industry lobbyists to investments in alternative forms of transportation.

In conclusion, the United States has not adopted high-speed trains as a mass transit option due to a lack of political will, high costs, existing infrastructure and cultural preferences for car travel. While there have been some efforts to develop high-speed rail networks in the United States, progress has been slow, and it is unclear whether these projects will ever be able to compete with the convenience and flexibility of car travel.
Are there private companies or lobbyists that are advocating and promoting high speed rail?
Yes, there are a number of private companies and lobbyists that are advocating and promoting high-speed rail in the United States. Some of the most well-known groups include:

High Speed Rail Alliance: The High Speed Rail Alliance is a non-profit organization that advocates for the development of high-speed rail in the United States. The organization works to educate the public about the benefits of high-speed rail and to lobby government officials for support.
American Public Transportation Association: The American Public Transportation Association is a trade association that represents the interests of public transportation agencies across the United States. The association supports the development of high-speed rail as a way to improve transportation options and reduce traffic congestion.
Rail Passengers Association: The Rail Passengers Association is a non-profit organization that advocates for the interests of rail passengers. The organization supports the development of high-speed rail as a way to provide a more efficient and environmentally friendly form of transportation.
These are just a few of the many groups that are advocating and promoting high-speed rail in the United States. The movement to build high-speed rail is growing, and it is likely that we will see more high-speed rail lines being built in the future.