If not, is anyone doing anything to improve this situation?
Sending packets over the internet across the farthest ends of the earth takes about 300ms roundtrip. What's preventing email from approaching this?
Latency is the biggest UX issue facing email IMHO, and a huge part of why it is continuing to lose ground vs alternative messaging systems, most of which are proprietary, but offer sub-second latency delivery. The world will become a worse place if the trend continues to its logical conclusion and proprietary silos eventually fully supplants email's remaining use cases.
The high average latency and even higher variance leads to people second guessing if an email they sent will ever arrive, and if an email they're expecting has ever been sent, resulting in crude workarounds like resend buttons becoming commonplace and seen as necessary, perpetuating the uncertainty around deliverability, and even further eroding trust in the system.
But most importantly, the latency problem makes email unsuitable for the most compelling use case for messaging platforms: real-time conversation.
Holding a spontaneous real-time conversation over email is painful, as anyone who has tried can probably attest. Both sides are constantly left wondering if the other side is simply taking their sweet time to reply, or if the email is just taking even longer than email usually takes to get delivered. Conversations that could have taken mere seconds end up taking minutes as a result.
This is why email has been consistently losing to messaging apps for fun conversations between friends where email's latency would suck much of the fun out of them, to Slack for mission critical work conversations where wasting time means literally wasting money, to live chat widgets for businesses looking to provide a customer support experience that delights, whereas conversations over email frequently tends to frustrate, the list goes on...
Solving the latency problem for email I believe is the key to slowing and possibly reversing the trend of email's slow but steady decline, and society will benefit massively from the continued prosperity of this rare miracle of an open system that managed to survive for so long despite all its shortcomings.