PHP: accessing an undefined array element yields a notice. Or does it? WTF, PHP?

G'day:
So we encountered this today:

<?php
$array = [1, 2, 3];

var_dump($array['id']); // this yields a warning
var_dump($array[0]['id']); // none of these do
var_dump($array[0][0]['id']);
var_dump($array[0]['id'][0]);

As indicated, this yields results:

C:\temp>php shite.php
PHP Notice:  Undefined index: id in C:\temp\shite.php on line 4
PHP Stack trace:
PHP   1. {main}() C:\temp\shite.php:0

Notice: Undefined index: id in C:\temp\shite.php on line 4

Call Stack:
    0.0002     353472   1. {main}() C:\temp\shite.php:0

C:\temp\shite.php:4:
NULL
C:\temp\shite.php:5:
NULL
C:\temp\shite.php:6:
NULL
C:\temp\shite.php:7:
NULL

C:\temp>

I think this behaviour is bloody daft. Accessing something that doesn't exist should be more than a notice, and it shouldn't then go ahead and return "null" anyhow. And giving a notice and returning null is possibly the worst way of combining possible actions here. What am I supposed to do with that? Other than bury my head in my hands a weep.

Now this is partially documented on the Arrays page of the docs:

Note:

Attempting to access an array key which has not been defined is the same as accessing any other undefined variable: an E_NOTICE-level error message will be issued, and the result will be NULL.

Note:

Array dereferencing a scalar value which is not a string silently yields NULL, i.e. without issuing an error message.

That's shit, but... well: it's not that surprising (I mean... it's PHP, right?). But how come

$array['id']

incurs the warning, but this doesn't:

$array[0]['id']

This just seems to make fairly unhelpful behaviour just that much less helpful.

I'm sure there's a reason for this. Not a good one, I hasten to add, but no doubt there's a reason.

Anyone know what it is?

Update:

Thanks to Dave (comment below) for pointing out there's a bug been raised for this: 68110.

Righto.

--
Adam