Since 2005 Rushida has of course lowered the 800m by another fraction, but many of the other distances have been lowered still more.
Does this mean that Coe's 1:41.73 was the equivalent of at least say 1:40.5 today, given that improved tracks, shoes etc. must account for the average 3-5% improvement in every other distance since 1981?
A further fact is that although Coe's 1:41 was a bit of an outlier being so far ahead of his rivals in 81, 800m times since the 80's have imrpoved much less than any other distance on the track for men. It's noticeable if you compare 800m times with 400m times. For example, the best 400m time in 1984 was 44.25, and the fifth best time 44.75. For 800m the best time was 1:41.73 and the fifth best time Coe's LA run of 1:43.64
In the Olympic year 32 years later (2016), the best 400m time was 43.03 and the fifth best time 44.01, so the elite were running about a second faster over 1 lap than in 1984. The best 800m time last year was 1:42.15 and the fifth best time 1:42.98 So the best time in 2016 was slower than the best time in 84 (which wasn't even the WR). The 5th best time 2016 would only be the fourth best time in 84. However the best 400m time in 84 wouldn't have got near the top 5 times in 2016.
Elite 400m runners today are about a second faster than 80's guys. 800m runners are perhaps a third of a second faster.
Why should this be? Was there a crop of 800m runners in the 80's that were just so damned talented and better than you'd expect?
You can even go further back, for example Peter Snell ran 1:44.3 on a grass track in the 1960's which is often compared to a 1:42 on a modern track. That time would rank in the top 5 today. Although a 43.96 was run at altitude in Mexico City in 68 I don't think any other 400m time got close to 44 seconds at sea level. Alberto Juantorena ran a 44.6 in 1977 that was the fastest 400m time that year.
If 800m times had progressed since the 80s as much as the other distances, and as much as the 400m, then the top guys should be running 1:40 at their best and threatening to crack 1:40.
I guess most answers will be related to drugs, but I don't think it can be explained entirely by PEDs.