There are ways to get around this:
- Use track with a wide ballast - there are some, but can't remember authors at the moment.
- Use a ballast spline and lay the track on that.
- Use a wide brush then cut the grass and dirt textures back on to the track.
I generally use the latter approach. I lay down a wider base ballast of cinders then place my track on that with some hints of gray ballast underneath. Where I live the railroad used cinders until they got rid of steam, and ballast was only used on the mainlines starting around WWII. Even to this day, there are places were the cinders still poke through on the shoulders, and is still found on abandoned branch lines and old abandoned ROW.
After I've placed my ballast down, cinders included, I then feather in the grass and dirt along the sides. Sometimes it's easier to put the grass and stuff down first then the track and ballast, and I think this actually looks better and less forced.
There are many, many ballast splines. I didn't like what was there so I made some using YARN track and various ballast textures such as the NS ballast texture from Jointed Rail. I edited the road texture and it became a wide ballast on my clone. I have both the regular street width and a 4-lane width. It also works for other situations such as ballast-covered areas, etc. This does come with caveats though. It's a bit extra work laying the track because the ballast spline has to be laid down first and has to be level, then the track goes on top and is not on the surface.
The wide-ballast track... I never liked how it looked and prefer the wider dirt along the tracks.