I think this is being framed a bit too much as “the U.S. is behind,” when there are a lot of factors at play that make it an apples-to-oranges comparison.
Policing in the U.S. is a very different job than in many other countries. Officers here are far more likely to encounter armed suspects, which raises the physical and tactical demands of the job. That alone can affect who chooses to apply, not just who gets hired.
Another piece is that U.S. policing isn’t one system. There are thousands of departments, all with their own hiring standards, recruiting efforts, and local culture. Some agencies have much higher percentages of women than others.
Also worth noting, this isn’t just about hiring. It’s about applicant pools. If fewer women apply for the job in the U.S., for whatever reason, be it risk, lifestyle, training demands, that will naturally affect the percentages.
There may well be cultural or institutional factors too, but it’s probably not as simple as “the U.S. doesn’t hire women” compared to other countries. Seems like a more complex mix of job risk, structure, and personal choice than a single explanation.