ICO Contract vs none?

[thinklab71]

Why do some ICO's have a ICO Smart contract and some don't?  I have seen some large ones not have contracts?  Is this so they can do bounties?

[wilberthh]

Why do some ICO's have a ICO Smart contract and some don't?  

Like... ethereum and neo smart contract?
Probably because project with smart contract tends to be considered as a scam project, therefore they create their own blockchain.

I have seen some large ones not have contracts?  

There are lots of ICO out there not relying on smart contracts. Like TravelFlex, HDAC, any many more.
Why should every ICO relies on those smart contract anyways?

 Is this so they can do bounties?

Every ICOs can create bounties regardless it has smart contract or not -_-

[fempat]

Smart contracts is basically Ethereum (am I right? ). Other Ethereum-like platforms like Waves also allow projects to be built upon them without the need for writing out smart contracts. Howver, Some projects might have but choose not to reveal it.

[cryptosifu]

It depends what platform the ICO is using.  If it's an Ethereum ERC-20 token ICO, then it will be on a smart contract.  If it's a different platform that doesn't have smart contracts, then the team will use other methods of distributing the coins or tokens.