I've been looking at a lot of these graphs, but to me, it seems very hard to infer much at all. The numbers are small, different countries probably had their first exposure at different dates and in different ways (a single person traveling, and spreading slowly, or a group entering the country and mingling?). With an exponential curve, it's hard to say just where you are on that curve this early on, and that makes a huge difference.
The numbers are small relative to the population of the respective countries. However, the rate they are increasing is alarming, and with the infected number being low compared to the total population, it means there's more dry wood to stock the fire.
Obviously, when a large percentage of the population has been infected, the curve cannot go on exponentially (when most of the forest is already gone). But at this point the curve can grow for quite a while, unless something drastic is done to slow it down. Remember the doubling every 3 days.
Regarding the number still being small relative to the population, it is already high enough to cause devastation in northern Italy. People who are interested can search the Web using the terms "Bergamo+coronavirus".
And different countries are indeed at different phases. They did not get "seeded" at the same point in time, and with the same number of seeds. The point is that the weeds all propagate with the same rate.
It has been said that many other European countries are about 1 week behind Italy at this point. One week is not a long time to wait to see if that is becoming true. Italy was unfortunate to have a headstart.
For example, Italy is at 27,980 now on 3/16/2020, while Germany is at 7,272. Will Germany get up to the 28,000 mark next Monday? Note that one week ago, Italy was at 9,172. Eight days earlier than today, on 3/8/2020, Italy was at 7,375, the same as Germany now.
Add to that the probable differences in reporting (I honestly don't know how we determine/compare the number of cases, when testing rates are very different?). IMO, South Korea is the only one I see that has a meaningful trend (and it's a good one!), but again, it's hard to say if that translates to other countries with different situations, controls, demographics, etc.
Hopefully, we get some clarity soon. But right now, it's like reading tea leaves, IMO.
-ERD50
I don't think anyone can say these numbers are over-reported. But whether under or over-reported, when the number of infections grows exponentially respectively at different locations, and northern Italy already runs out of hospital beds a week or two ago and crematorium running 24/7, it should not be surprising that European countries are all shutting down borders and instituting lockdown.