Note that in all of these cases, the shell (not echo, ls, or printf) is expanding the pattern to produce a list of files. Which command you should use to process that list of files depends on what you want to do with the files in that list.

Note that there are at least three different versions of echo: AT&T's UNIX System V echo, University of California's Berkeley Software Distributions's (BSD's) echo, and the Linux GNU echo each of which have different options and each of which handle backslash characters in operands differently. If you want to write portable code, never use echo if the first character of the first operand might be a minus sign character or if any character in any operand might be a backslash character. (And you can't use -- as a first operand to skip over options and treat them as operands because some versions of echo will print the -- instead of ignoring it.) Use ls if some of the files given to it might be directories and you want ls to also list the files in the directories named by that operand, but note that the format of the output of ls (when no options are specified and the 1st operand does not begin with a minus-sign character) may differ if its standard output is directed to a terminal than if its standard output is directed to a pipe or a regular file. Use printf (with a first operand that specifies the format you want used to display any remaining operands) if you want to specify the output format and want the output to be portable to any operating system.
The first operand to printf is always interpreted as a format string to control the display of any remaining operands. If the first operand does not contain any percent-sign characters, remaining operands will be ignored.

When the first operand is "\t%s\n" or '\t%s\n', each remaining operand will be printed as a string (%s) following a tab character (\t) and followed by a newline character (\n). If the first operand was '\t%s\t%s\t%s\t%s\n', up to four following operands will be printed each with a leading tab character and with the last one followed by a newline character. (If the number of remaining operands is not an even multiple of 4, the final unmatched %s format specifiers will act as if empty strings were supplied to be printed.)

When you didn't supply a format string as a first operand to printf, the first file operand you you gave it was interpreted as a format string. If it didn't contain any percent-sign characters followed by other characters that printf could interpret as a valid format specifier, remaining operands would be ignored.
If any of your filenames contain space, tab, or newline characters; files you want to remove will not be removed, files you didn't want to remove may be removed instead, and other commands could be executed.
I hope this helps,
Don