Thanks for the advice, and I know personal networking is important but I don't really like to straight out ask people if they can hire me (though I did ask two professors I've never met). I am nearly certain most of the companies I've applied to haven't looked at my application, but I just don't get why they would post seemingly expensive ads on Indeed and LinkedIn. It feels disingenuous.
I don't really like to straight out ask people if they can hire me
That is a success-limiting preference and I would encourage you to start preferring other things. If it helps, pretend you're just on a recon mission not actually looking for a job but trying to ascertain whether there is a you-sized hole in the project that they're running which you are legitimately interested in. Scientists love talking about their babies to anyone who will listen.
"So what are you working on this summer?"
"We're programming FPGAs to do automatic detection of human language in content going over the wire using bloom filters."
"Oh that sounds interesting. Who are you working with?"
"Dr. Foo, Dr. Bar, and 3 graduate students."
"Who is your Unicode expert?"
"We don't have one."
"Really? That's unfortunate -- you're solving it with low-level byte manipulation so if you don't have an intuition for what a bytestream of UTF-8 in Russian actually looks like that might be a bit difficult. Mind if I have a quick go at the blackboard?"
"Be my guest."
"So let's take the UTF-16 case since it's easier to understand..."
5 minutes later
"Huh, thanks for the explanation. I wish we could have you around every day."
"Do you hire undergraduate research assistants?"
"Yes."
"Then you can!"
[Lightly fictionalized from an actual research assistantship.]
Another success route here involves finding Professor Foo of the Interesting Funded Research sometime in the fall or spring, telling Foo that his research is cool, and then asking if you could you help out (volunteer). The answer will likely be "yes", and then, providing you're being a relatively functional person, you're now a strong candidate & provisionally in the rotation for the next blob of funding coming along.
(This has happened in multiple scenarios to various friends and self).
Like Patrick mentions in his reply, you should try to hack your psychology to get more comfortable with directly but politely asking for things you want.
One trick that works for me is to tell myself "Let's try it and see what happens". Curiosity is a strong motivator.
Don't get stressed about asking people to hire you. I am in a mechanical engineering research lab and we will have two undergrads and a master's student from France in or lab this summer mostly doing computer work. They are mostly here because they emailed Dr. Bifano and just asked if they could work in his lab over the summer. If you know any professors, you could ask them if they have friends that are looking for someone. Undergrad help is cheap, and lots of professors are interested in hiring someone for a few months. Summers are especially nice because if things don't go well it is easy to let them go afterwords.
