"We have to buy more eggs."
Translation:Tenemos que comprar más huevos.
There's a subtle difference between - need to and have to, but an important one. They're not interchangeable.
I need to buy eggs IF I want to make an omelette tonight, but I can't make it if if I don't have them, so I'll make something else. This implies choice.
I have to buy eggs to make an omelette tonight, because I can't make an omelette without eggs. This implies no choice.
I agree that there is a slight difference in meaning between "we need to" and "we have to". You can swap the two 90% of the time, but not 100%. There is also probably a difference in usage between "necesitamos" and "tenemos que", although I've yet to hear a Spanish speaker explain what that difference actually is.
But aren't those differences small compared to the mismatch between almost any English phrase and its translation into Spanish? Translation is such a rough business that nitpicking the difference between "necesitamos" and "tenemos que" as a translation for "we have to" seems silly.