It depends on the person I think.
We had out of town guests invited to my shower because almost everyone was out of town

But my bridesmaids kept the list fairly short -- only the people that I was close with, not every female on the wedding invite list. Most came, except some of my college friends who would have needed to take a plane. I've been invited to all of their showers, even though I would need to fly as well. Most of the time I decline, but send a gift. They've done the same thing.
I was recently invited to a shower where I'm friends with the groom. I don't know the bride that well (we've met maybe 3 times?) and I don't know any of her friends. I thought it was weird to be invited. (Shower in Philadelphia) So I declined and didn't send a gift.
Then I got one a month later for a shower for by my husband's friend's bride. (Shower in Vermont) I've met the bride and groom once. So I thought it had to be a gift grab, but after talking with my husband I learned that apparently the groom's mother is notorious for inviting everyone to everything. So again I declined and didn't send a gift.
ETA: My Maid of Honor and I had quite the discussion with my husband about inviting his Grandmother. We knew she wouldn't travel, weren't looking for a gift, but didn't want her to feel like we wouldn't have wanted her there. My husband was worried about her thinking that she needed to send a gift. I was worried about making her feel included. In the end, we included her on the guest list, but spoke to his Mom about making sure she knew that we knew she probably wouldn't be able to come and wanted to her to know if she could, she was absolutely wanted to be there but weren't looking for a gift. I think it was the best solution.