Arduino SAMD Boards not displaying that information is also what I've experienced. The relevant parts for Arduino AVR Boards (which does display this information) is here:
compiler.size.cmd=avr-size
and here:
## Compute size
recipe.size.pattern="{compiler.path}{compiler.size.cmd}" -A "{build.path}/{build.project_name}.elf"
recipe.size.regex=^(?:\.text|\.data|\.bootloader)\s+([0-9]+).*
recipe.size.regex.data=^(?:\.data|\.bss|\.noinit)\s+([0-9]+).*
recipe.size.regex.eeprom=^(?:\.eeprom)\s+([0-9]+).*
So you can see that the avr-size tool outputs all the necessary numbers and then a regular expression is used to parse the output.
In the case of Arduino SAMD Boards:
compiler.size.cmd=arm-none-eabi-size
## Compute size
recipe.size.pattern="{compiler.path}{compiler.size.cmd}" -A "{build.path}/{build.project_name}.elf"
recipe.size.regex=\.text\s+([0-9]+).*
So the logical first point of investigation would be the SAMD boards arm-none-eabi-size tool to see what information it is capable of providing.