What PDF is
PDF describes a page: glyphs at coordinates, not rows and columns. A table in a PDF is a visual arrangement, not a data structure.
Reports, invoices, statements and anything sent to be read rather than processed.
What ASCII Table is
An ASCII table is a grid drawn with plus signs, dashes and pipes. It renders identically in every terminal and every font.
Command line output, code comments, plain text email and commit messages.
What changes when you convert PDF to ASCII Table
Every character in a text-based PDF carries its position on the page. Characters sharing a baseline are one row. Columns are found from the vertical strips no character ever occupies, which is why extraction works cleanly on a document laid out with spacing and badly on one laid out with ruled lines. A header repeated at the top of each page is detected and dropped rather than landing in the middle of the data.
Column widths are measured in display columns rather than characters, so a table with CJK or emoji content still lines up.
What carries over from PDF to ASCII Table
PDF records 2 things about a table that ASCII table has no way to hold.
A line break inside a cell ends the row in ASCII table, so line breaks are replaced rather than carried through.
ASCII table marks its header cells differently from its data cells, so the first row is written with that marker.
Anything visual in the PDF - weight, alignment, colour, column widths - has no counterpart in ASCII table and is dropped. The values are what survives.
This is the direction that recovers structure: PDF has no table in it to read, only an arrangement that looks like one, so the rows and columns are inferred rather than read.