Cover and AOE spells

[Marcloure]

Let's say you cast a spell in an open flat field, filled with people in each square.

Casting fireball and lightning bolt, which targets have cover (either half or three-quarters)? Rules say targets behind cover do gain bonus to Dexterity saving throws (PHB 196), and nothing there says cover doesn't affect spells.

To help I have the image below.
F: fireball
L: lightning bolt

By the rules (PHB p196 and p204, DMG p251), it seems that:
F1 has no cover
F2, F3 and F4 have 1/2 cover
F2*, F3* and F4* have 3/4 cover
L1 has no cover
L2 to L20 have 1/2 cover

https://scontent.fplu4-1.fna.fbcdn.net/v/t1.15752-9/48416775_277650516287034_8035908648611872768_n.png ?_nc_cat=106&_nc_eui2=AeFqC5Nj__NF0KvKm9tqzLs0r_RN0TtabvFa9Mipt icspLooniJdb526FOWrgBlH8sNZ1yOvSjnZwHsVYwp3ca-Y_k3pJ2IcHvRI3SCOwbf36Q&_nc_ht=scontent.fplu4-1.fna&oh=d3a90b779b4124681d9bb2e03cf7989b&oe=5C9B2C5E

But fireball says it goes around corners, does that mean it ignores cover? What do you think?

[sophontteks]

Fireball ignores cover. Nothing says it effects spells. Cover is vs. attacks.

[Marcloure]

Fireball ignores cover. Nothing says it effects spells. Cover is vs. attacks.

I can agree with fireball not being affected by cover.

But as the general rule, in the rules section, nothing says it only matters for attacks. It even says cover grants bonus to Dexterity saving throws.

[PhoenixPhyre]

I can agree with fireball not being affected by cover.

But as the general rule, in the rules section, nothing says it only matters for attacks. It even says cover grants bonus to Dexterity saving throws.

This is correct. Fireball is only affected by total cover, all other Dex-save AoEs (that don't include a "spreads around corners" clause) are affected by any cover. Note that sacred flame explicitly ignores cover (despite provoking a DEX save).

[JNAProductions]

Pretty sure cover gives the same bonus to both AC and Dex saves.

[sophontteks]

I can agree with fireball not being affected by cover.

But as the general rule, in the rules section, nothing says it only matters for attacks. It even says cover grants bonus to Dexterity saving throws.
What I mean is. The rules state how cover works. Like as someone pointed out cover also increases your dex save. What it says it does is what it does. The way spells interact with cover is written in the spell description if it is any different.