Псевдонимы недоступны в той же строке или в той же функции, где они определены.
со страницы руководства Bash:
The rules concerning the definition and use of aliases are somewhat
confusing. Bash always reads at least one complete line of input
before executing any of the commands on that line. Aliases are
expanded when a command is read, not when it is executed. Therefore,
an alias definition appearing on the same line as another command does
not take effect until the next line of input is read. The commands
following the alias definition on that line are not affected by the new
alias. This behavior is also an issue when functions are executed.
Aliases are expanded when a function definition is read, not when the
function is executed, because a function definition is itself a com‐
pound command. As a consequence, aliases defined in a function are not
available until after that function is executed. To be safe, always
put alias definitions on a separate line, and do not use alias in com‐
pound commands.
For almost every purpose, aliases are superseded by shell functions.
Справочное руководство Bash говорит
Практически для всех целей функции оболочки предпочтительнее вместо псевдонимов.
вместо последнего предложения выше [выделено мной]. Я считаю псевдонимы удобством командной строки, а не тем, что следует использовать в сценариях (включая те, которые состоят исключительно из bash -c однострочников).