My understanding is that large MNC’s appetite for social responsibility to protect their brand, image and reputation hence there is a strong expectation to have tax and legal DD regardless of the size of deal. Basically it helps in reducing the risk of buyer unseen liabilities and risk exposures associated with a commercial deal.
In my view, Tax & Legal DD is key when acquiring / merging with a company, as the target could have certain tax / legal issues that might blow up and destabilize the MergeCo. It might even lead to unlawful conduct if the target is operating illegally such as conducting tax fraud
It is essential to fully understand the jurisdictions the tax structure to avoid any future obligations that might affect the financial stability to the buyer