There is plenty of airspace for everyone. We just need to know when and where the jets are coming from before we can see them.
The technology for this is available but the charities are hard pushed to afford £50-60k per airframe for TCAS. (some are still struggling just to stay airborne).
The recent Strensham incident has apparently got the attention of the NHS, so perhaps some progress, re TCAS funding, might come out of this.
(Local NHS trusts supply the Paramedics who crew the HEMS)