rather than + bare infinitive or to-infinitive?

[Mori]

As far as I know, we use a bare infinitive or a gerund after rather than:

We can use an infinitive (without to) or an -ing form after rather than in this case.
She prefers to make toys for her children rather than buy/buying them.
I would prefer to stay at home rather than drive/driving to your mother's.

Source: Michael Swan, Practical English Usage fourth edition, entry 560

When we use rather than with a verb, we use the base form or (less commonly) the -ing form of a verb:
Rather than pay the taxi fare, he walked home. (or Rather than paying the taxi fare, he walked home.)
Not: Rather than to pay …

Source: English Grammar Today

Nevertheless, I saw the following today:

Normally, to is used after prefer and preferable, not than: I prefer Brahms to Tchaikovsky; a small income is preferable to no income at all. However, than or rather than should be used to link infinitives: I prefer to walk than/rather than to catch the train

Source: Collins English Dictionary

I wonder what you think. Is it a mistake?

 

[jutfrank]

No, it isn't, but it isn't necessary.

 

[Mori]

No, it isn't, but it isn't necessary.

Ellipsis, right?

 

[jutfrank]

Ellipsis, right?

Yes. I generally teach my learners not to use the 'to' because it isn't necessary. It's not that uncommon to use it, though.