That was not always the case. Once upon a time, there was the Office of Technology Assessment[0]. As to why it is no more, one need look no further than Newt Gingrich[1][2]:
> OTA was abolished (technically "de-funded") in the "Contract with America" period of Newt Gingrich's Republican ascendancy in Congress. According to Science magazine, "some Republican lawmakers came to view [the OTA] as duplicative, wasteful, and biased against their party."[0]
0 - https://en.wikipedia.org/wiki/Office_of_Technology_Assessmen...
1 - https://www.theatlantic.com/technology/archive/2012/10/the-m...
2 - https://economix.blogs.nytimes.com/2011/11/29/gingrich-and-t...