Significant types in ETL-style applications typically come from outside (e.g. a certain CSV column in the input file contains a date in YYYYMMDD format, or maybe YYYYDDMM, figure it out, and don't forget time zones or your accounting will go wrong).

Then types are mostly complex but obvious and easily deducted (e.g. multiplying matrices of compatible shapes necessarily gives a matrix of a certain shape, why should the program say anything more detailed or lower-level than "do a matrix multiplication" or "do a tensor product"?); they are an often dynamic and unpredictable property of the data, not a useful abstraction.