When walkout basement door installation is possible in Louisville
If the lot slopes enough that the basement floor sits at or near ground level somewhere along the perimeter, a door can go there. Plenty of Louisville lots do, particularly on the east side and anywhere near the creeks and ravines.
Where the grade is close but not quite there, excavating an areaway with steps up to grade is an option. It costs more than a window well and far less than regrading the yard. Where the house sits flat on its lot, this is off the table and an egress window is the answer.