Thank you for taking the time to write to us, but this is not
a bug. Please double-check the documentation available at
http://www.php.net/manual/ and the instructions on how to report
a bug at http://bugs.php.net/how-to-report.php

This is by design. Passing null does not always indicate "skip this parameter and use the default", null may also have a semantic meaning.

The behaviour you want can be easily achieved in combination with the ?? operator, something like:

function get(string $id, ?int $limit = 1, ?string $type = 'standard', ?array $options = []){
    var_dump($limit ?? 1);
    var_dump($type ?? 'standard');
    var_dump($options ?? []);
}

In combination with private class constants, you can also avoid specifying the default value more than once in code, retaining correct information reported by reflection/IDEs etc:

class Foo
{
    private const DEFAULT_LIMIT = 1;
    private const DEFAULT_TYPE = 'standard';
    private const DEFAULT_OPTS = [];

    public function get(string $id, ?int $limit = self::DEFAULT_LIMIT, ?string $type = self::DEFAULT_TYPE, ?array $options = self::DEFAULT_OPTS)
    {
        var_dump($limit ?? self::DEFAULT_LIMIT);
        var_dump($type ?? self::DEFAULT_TYPE);
        var_dump($options ?? self::DEFAULT_OPTS);
    }
}

Having the engine assume that null implies the default means you couldn't pass an actual null value.

An idea to use "default" as a keyword was declined. https://wiki.php.net/rfc/skipparams
Named parameters were another approach. https://wiki.php.net/rfc/named_params

If you have a new idea that you want to propose then check out the RFC process. https://wiki.php.net/rfc/howto
Otherwise this should be addressed in code like how @daverandom showed.