I remember when we used to get king-size cigarette papers printed as a dollar bill............. er ............. ah........ I see now......
Uk, that is a perfectly good joint for your storage racks. No good for a frame that's going to have to be moved around, because it'll soon loosen up.
Shelving should be rigid, and preferably anchored to a wall for stability. So that joint is fine.
The screws the others have mentioned are usually "twin-thread" or similar. That is... you can drive them straight in with no pilot hole needed. I always use something like that.
But......................... for you ............. you will possibly struggle to drive them easily without a pilot hole.
I usually have two cordless for this. One with a 3mm steel drill bit for the pilot hole... and the other one with a screwdriver bit (pozidrive.)
The other reason for this is that, without pre-drilling, you can easily split the wood. A pilot hole stops that from happening.