ecommerce conversion varies widely

I need to bounce something off you all.

Explaining all this is a real bear - please let me know if you need me to clarify a particular point.

I see ecommerce conversion rates varying by huge percentages. Some of this seems to make sense - but is this really "normal"? Maybe some of this is expected, but are there technical ways to improve on some of these lower conversion rates?

The objective, of course, is to optimize the system so as to maximize the profit and minimize the shopping cart abandonment.

Our highest volume visitor (as defined by browser type) is well below average (1.44%) at about .5%

Our next highest volume visitor is almost 3X that, right at average.

In the Top 10, 8 are better than the 1% range, and the remaining 2 are .5% and .3%.

The highest volume browser accounts for 20% of traffic but only 12% of revenue. The next highest volume browser accounts for 9% of traffic but 15% of revenue.

I know these high traffic / low converters are mobile browsers.

Is there a way to modify the cart so that we can get a better or more consistent conversion rate on these mobile customers?

I also see that some flavors of Chrome are converting at 1% - but one particular flavor is converting at over 2%.

Overall, of the 200 types of browsers tracked, about 90 convert at better than 1% - and the remaining 110 are less than 1%.

So my question is this - should ecommerce conversion rates vary so widely?

It seems to me if, say the top 10 were more closely clustering around an average of 1%, we'd be making much more money.

We have engaged in some rather sophisticated conversion improvement testing and we are seeing good results, but only in certain sectors.

Before I even go down the road on this with the client and the developers, I need to get a sense from WebmasterWorld if this even makes sense to pursue.

As always, thanks so much.