Technology is very important in determining the size and scope of an industry. Home countries oppose export of technology because this would provide their trade secrets to other countries.
Technology defines the quality of a product manufactured. Exporting the technology used in home country is not viable because this way the countries lose their comparative advantage to other firms. When other countries would have the same technology they would be able to make the same products. This way there would be less and less demand of products made by home country because it would be readily available in the market.That is why technology is considered as the barrier to entry in an industry.
The international market is very demanding and complex. It is not very easy to understand its mechanism. Product decisions are made considering various different things such as technology, level of similar products internationally, product quality, international standards compliance etc.
Home Countries Oppose the export of Technology because this way they can protect their industry.
When a country produces a product with its own technology, it is actually the owner of that technology. This technology gives the country an advantage over the countries that do not have that technology. This way they can sell their products based on that technology to other countries. If they export their technology, other countries will get the technology to make that product and this way, will feel no need for the home country's product.
So opposition of export of technology protects the home industry.
Some of the MNC's imports stem from their subsidiaries, the volume of imports of the country tends to increase, given the decrease in exports & increase in imports, the balance of trade tends to be adverse to the home country.
Job generated from the technology transfer & innovation of a new technology with the help of old one, will benefit the host country citizens. Hence it also opposed by Home country Labour Unions.