DC is unique among those cities because it is federal territory where the federal government has exclusive jurisdiction, according to the constitution. It's harder to deploy the National Guard to St. Louis, for example, because you also have to deal with the government of Missouri (and probably that of Illinois, too, since the metro area spans both states).
In fact, a senator famously called for troops to be deployed to those cities in the height of the unrest in 2020[0]. He was excoriated for it by his political opponents, and the editor in charge of the NYT opinion pages resigned over allowing that piece to be published. So there are people who would like to see dramatically stronger law enforcement everywhere, not just DC.
[0]: https://www.nytimes.com/2020/06/03/opinion/tom-cotton-protes...