A trail identification algorithm would determine if a pixel value is valid -- reject it if it falls within a trail.
How do you determine what a trail is, though? Does such an algorithm exist? And further, during integration, you operate on pixel stacks. You are not operating on "images"...so, there is no spatial information to work with. You operate on a "vertical" series of pixels that all correlate to the same exact location, but acquired at different points in time. So, there is no "trail" to be identified when integrating an image.
Currently, image integration programs utilize simple statistical algorithms to identify and reject outliers. They locate the mean, determine the (optimized, possibly) standard deviation, then allow you to reject anything some number of sigma from that mean. Sigma, Kappa-Sigma, Winsorized Sigma. There is also Linear Fit rejection if you use PixInsight. These are not identifying trails, though. They are working with the statistical distribution of samples for a single pixel at a time...the locus around which these samples are distributed, their dispersion, and they identify those that are more widely dispersed than the majority. With two samples, you cannot do this. With three, you might be able to do something, but the results are likely to be skewed. With many samples, you can more accurately locate the mean, more accurately compute sigma, and more accurately identify which pixels actually fall well enough outside of that dispersion to actually qualify as an outlier...in that particular vertical pixel stack.
You then repeat this process for each and every pixel location. There are no "trails" to be identified and removed. You might be able to do some kind of large scale rejection on each individual frame before integration. PixInsight supports this with Local Normalization. Local normalization is not really intended to remove trails, though...it is a normalization process that is intended to perform normalization at a scale less than the whole entire field (which is what image integration already does), but it can be very difficult to apply properly, and without proper application it can introduce artifacts rather than eliminate them, or trade one set of artifacts for another.
Further, these are all tradeoffs we have to make to get a good image. Local normalization in PixInsight is NOT a fast process by any means, and if you aim to do it right you are usually stuck running multiple passes until you find the settings that work. If we have to do some kind of large scale pre-processing to clean up our frames, especially something that could add a significant amount of time to our processing, BEFORE integration, that right there indicates how severe the problem is of having so many satellites in LEO. I have done hours-long pre-processing in the past. I've done local normalization. I've integrated hundreds to thousands of frames with lots of trails in them. I don't want to have to spend that kind of time processing my images...I hardly have the time to process the data I have the way I process now, and I've spent quite a lot of effort optimizing my routines to give me clean results at a minimal time investment.
These satellites will be a problem. Again, it isn't just about StarLink...StarLink is just the herald of what is to come. There are going to be tens of thousands of satellites in LEO. Right now, there are 4900 satellites in ALL of earths orbital bands...which means there are fewer than that in LEO. We are adding tens of times the number of satellites we have now up there. It is going to be a problem... I just hope it doesn't end up a disaster...as at least as long as they can control these things, they could eventually guide them to burn up in the atmosphere (and I can only hope that at some point we realize our folly here and try to correct it...) Once we experience Kessler syndrome, though...tens of thousands of satellites become millions upon millions of pieces of debris, some of it small, some larger chunks, all uncontrolled, and a lot of which we will be able to see in our photos. Kessler syndrome is really what I fear...I see it as an inevitability if we put so many satellites up there (especially since a lot of this is mostly billionaires playing popularity games here), and once it happens... Thousands of satellites will be the least of our problems...