They can and do, but struggle with the following problems: - Assessing English proficiency. It's hard to do if you can't speak English yourself, and so they tend to fall back on numeric measures like test scores (which someone who has grown up overseas and speaks English at a native level might not bother to take, and someone who has grinded for a test might pass while having mediocre communication ability).

- Paying fluent English speakers enough to attract and keep them. Japanese salaries are low, and they tend to start all new hires at the same level and give gradual raises over time, with little consideration for special skills such as English ability. Fluent English speakers often either go overseas or work at international companies that pay more and also have better work-life balance.

- Many Japanese companies are rigid and formal in culture. Japanese people who have spent significant time overseas struggle to adjust, and they are not given the cultural leeway that a foreigner might be given.

- Control. There's a significant number of managers who are either micromanage-y or insecure about their own English ability and therefore can't just let a fluent speaker do their job without burdening them with nitpicky rules or insisting on rewriting things themselves.

The usual reasons organisations find it impossible to do things: inability to maintain incentive alignment within the company, manifesting as unwillingness to reward genuine bilingualism with enough money/status to incentivise it.