Nested transaction can cause async transaction state

Let's consider this code 

    begin try
    begin transaction;

    --control_proc_id:      convert_camel_case_to_snake_case
    --template_id:          convert_camel_case_to_snake_case
    --prog_object_item_id:  convert_camel_case_to_snake_case
    --template_description: 

    declare @to_tag_id big_text = dbo.camel_case_to_snake_case(@input)

    exec  task_rename_tag
          @from_tag_id = @input
    ,     @to_tag_id   = @to_tag_id

    if @@trancount > 0 -- ALWAYS CHECK FOR ACTIVE TRANSACTIONS

    commit transaction;
    end try
    begin catch
        if @@trancount > 0
        begin
            rollback transaction;
        end;

        ; -- Throw original exception
        throw;
    end catch;

When the task “task_rename_tag” invokes a rollback, the calling procedure will try to commit the transaction when there is no guard that checks @@trancount.
 

I think it would be always a best practice to always check trancount, to prevent illegal commit or rollback. The “atomic” templates that are used can be easily expanded with the safeguard if @@trancount > 0

Is there any reason it isn't implemented, should I treat transactions differently?